Document and Entity Information
Document and Entity Information - USD ($) | 12 Months Ended | |
Dec. 31, 2016 | Feb. 22, 2017 | |
Entity Information [Line Items] | ||
Entity Registrant Name | Northwest Pipeline LLC | |
Entity Central Index Key | 110,019 | |
Document Type | 10-K | |
Document Period End Date | Dec. 31, 2016 | |
Amendment Flag | false | |
Document Fiscal Year Focus | 2,016 | |
Document Fiscal Period Focus | FY | |
Current Fiscal Year End Date | --12-31 | |
Entity Filer Category | Non-accelerated Filer | |
Entity Common Stock, Shares Outstanding | 0 | |
Entity Well-known Seasoned Issuer | No | |
Entity Voluntary Filers | No | |
Entity Current Reporting Status | Yes | |
Entity Public Float | $ 0 |
Statement of Comprehensive Inco
Statement of Comprehensive Income - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | |
OPERATING REVENUES | $ 474,029 | $ 472,994 | $ 470,050 |
OPERATING EXPENSES: | |||
General and administrative | 52,343 | 57,105 | 62,085 |
Operation and maintenance | 79,514 | 73,128 | 74,191 |
Depreciation | 101,672 | 100,554 | 99,138 |
Regulatory debits | 3,510 | 2,550 | 1,487 |
Taxes, other than income taxes | 17,835 | 17,151 | 16,987 |
Total operating expenses | 254,874 | 250,488 | 253,888 |
OPERATING INCOME | 219,155 | 222,506 | 216,162 |
OTHER (INCOME) AND OTHER EXPENSES: | |||
Interest expense | 39,164 | 46,024 | 46,095 |
Allowance for equity and borrowed funds used during construction | (1,371) | (1,619) | (573) |
Miscellaneous other (income) expenses, net | 907 | (595) | 87 |
Total other (income) and other expenses | 38,700 | 43,810 | 45,609 |
NET INCOME | 180,455 | 178,696 | 170,553 |
CASH FLOW HEDGES: | |||
Amortization of cash flow hedges into Interest expense | (28) | (62) | (62) |
COMPREHENSIVE INCOME | $ 180,427 | $ 178,634 | $ 170,491 |
Balance Sheet
Balance Sheet - USD ($) $ in Thousands | Dec. 31, 2016 | Dec. 31, 2015 |
CURRENT ASSETS: | ||
Cash | $ 0 | $ 169 |
Receivables: | ||
Trade | 42,702 | 42,669 |
Affiliated companies | 1,321 | 1,441 |
Advances to affiliate | 45,137 | 171,867 |
Other | 598 | 14,051 |
Materials and supplies | 10,106 | 10,183 |
Exchange gas due from others | 3,869 | 3,733 |
Exchange gas offset | 0 | 201 |
Prepayments and other | 5,740 | 6,164 |
Total current assets | 109,473 | 250,478 |
PROPERTY, PLANT AND EQUIPMENT, at cost | 3,319,516 | 3,306,205 |
Less-Accumulated depreciation | 1,424,855 | 1,367,632 |
Total property, plant and equipment, net | 1,894,661 | 1,938,573 |
OTHER ASSETS: | ||
Deferred charges | 2,122 | 2,110 |
Regulatory assets | 34,900 | 40,853 |
Total other assets | 37,022 | 42,963 |
Total assets | 2,041,156 | 2,232,014 |
Payables: | ||
Trade | 11,243 | 14,363 |
Affiliated companies | 7,293 | 11,959 |
Accrued liabilities: | ||
Taxes, other than income taxes | 11,435 | 11,033 |
Interest | 3,501 | 4,045 |
Exchange gas due to others | 4,169 | 2,252 |
Exchange gas offset | 1,428 | 0 |
Customer advances | 1,893 | 5,573 |
Other | 5,224 | 3,417 |
Long-term debt due within one year | 184,924 | 174,837 |
Total current liabilities | 231,110 | 227,479 |
LONG-TERM DEBT | 334,236 | 518,583 |
OTHER NONCURRENT LIABILITIES: | ||
Asset retirement obligations | 60,762 | 82,454 |
Regulatory liabilities | 30,717 | 26,802 |
Other | 7,316 | 6,108 |
Total other noncurrent liabilities | 98,795 | 115,364 |
CONTINGENT LIABILITIES AND COMMITMENTS (Note 3) | ||
OWNER'S EQUITY: | ||
Owner's capital | 1,073,892 | 1,073,892 |
Retained earnings | 303,123 | 296,668 |
Accumulated other comprehensive income | 0 | 28 |
Total owner's equity | 1,377,015 | 1,370,588 |
Total liabilities and owner's equity | $ 2,041,156 | $ 2,232,014 |
Statement of Owner's Equity Sta
Statement of Owner's Equity Statement of Owner's Equity - USD ($) $ in Thousands | Total | Owner's capital | Retained earnings | Accumulated other comprehensive income (loss) |
Balance at beginning of period at Dec. 31, 2013 | $ 1,073,892 | $ 349,419 | $ 152 | |
Net income | $ 170,553 | 170,553 | ||
Cash distributions to parent | (234,000) | (234,000) | ||
Reclassification of unrecognized gain into earnings | (62) | (62) | ||
Balance at end of period at Dec. 31, 2014 | 1,359,954 | 1,073,892 | 285,972 | 90 |
Net income | 178,696 | 178,696 | ||
Cash distributions to parent | (168,000) | (168,000) | ||
Reclassification of unrecognized gain into earnings | (62) | (62) | ||
Balance at end of period at Dec. 31, 2015 | 1,370,588 | $ 1,073,892 | 296,668 | 28 |
Net income | 180,455 | 180,455 | ||
Cash distributions to parent | (174,000) | (174,000) | ||
Reclassification of unrecognized gain into earnings | (28) | (28) | ||
Balance at end of period at Dec. 31, 2016 | $ 1,377,015 | $ 303,123 | $ 0 |
Statement of Cash Flows
Statement of Cash Flows - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | |
OPERATING ACTIVITIES: | |||
Net income | $ 180,455 | $ 178,696 | $ 170,553 |
Adjustments to reconcile net income to net cash provided by (used in) operating activities: | |||
Depreciation | 101,672 | 100,554 | 99,138 |
Regulatory debits | 3,510 | 2,550 | 1,487 |
Gain on sale of property, plant and equipment | 0 | 0 | (70) |
Amortization of deferred charges and credits | 898 | 762 | 894 |
Allowance for equity funds used during construction | (953) | (1,099) | (391) |
Changes in current assets and liabilities: | |||
Trade and other accounts receivable | 845 | (137) | 395 |
Affiliated receivables | 120 | 598 | 38,388 |
Exchange gas due from others | (1,617) | 7,349 | (1,433) |
Materials and supplies | 77 | (117) | 203 |
Other current assets | 424 | (1,283) | (1,326) |
Trade accounts payable | (1,560) | 158 | (4,958) |
Affiliated payables | (4,666) | (1,184) | 2,007 |
Exchange gas due to others | 1,617 | (8,095) | 2,179 |
Other accrued liabilities | (2,089) | 5,410 | (3,095) |
Changes in noncurrent assets and liabilities: | |||
Deferred charges | (7,275) | (2,633) | (2,087) |
Noncurrent liabilities | 12,810 | 9,164 | 11,000 |
Net cash provided by operating activities | 284,268 | 290,693 | 312,884 |
FINANCING ACTIVITIES: | |||
Payments of long-term debt | (175,000) | 0 | 0 |
Cash distributions to parent | (174,000) | (168,000) | (234,000) |
Other | 0 | 0 | (622) |
Net cash used in financing activities | (349,000) | (168,000) | (234,622) |
Property, plant and equipment: | |||
Capital expenditures, net of equity AFUDC | (80,383) | (86,289) | (79,413) |
Contributions and Advances for Construction Costs | 1,308 | 1,499 | 3,056 |
Disposal of property, plant and equipment, net | (1,280) | (1,075) | 5,728 |
Advances to affiliates, net | 126,730 | (36,813) | (15,886) |
Proceeds from insurance | 18,188 | 0 | 8,274 |
Net cash provided by (used in) investing activities | 64,563 | (122,678) | (78,241) |
NET (DECREASE) INCREASE IN CASH | (169) | 15 | 21 |
CASH AT BEGINNING OF PERIOD | 169 | 154 | 133 |
CASH AT END OF PERIOD | 0 | 169 | 154 |
Supplemental Cash Flow Elements [Abstract] | |||
Increases to property, plant and equipment | (72,432) | (73,931) | (71,207) |
Changes in related accounts receivable, accounts payable, and accrued liabilities | (7,951) | (12,358) | (8,206) |
Capital expenditures, net of equity AFUDC | $ (80,383) | $ (86,289) | $ (79,413) |
Summary of Significant Accounti
Summary of Significant Accounting Policies (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Organization, Consolidation and Presentation of Financial Statements [Abstract] | |
Summary of Significant Accounting Policies | SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Corporate Structure and Control Northwest Pipeline LLC (Northwest) is indirectly owned by Williams Partners L.P. (WPZ), a publicly traded Delaware limited partnership, which is consolidated by The Williams Companies, Inc. (Williams). On February 2, 2015, WPZ was merged into Access Midstream Partners, L.P. (ACMP), another publicly traded limited partnership consolidated by Williams. ACMP was the surviving partnership and was subsequently renamed WPZ. At December 31, 2016, Williams owned an approximate 60 percent interest in WPZ, comprised of an approximate 58 percent limited partner interest and all of the 2 percent general partner interest. In January 2017, Williams permanently waived the WPZ general partner’s incentive distribution rights, converted its 2 percent general partner interest in WPZ to a non-economic interest, and purchased additional WPZ common units. Following these transactions, Williams owns a 74 percent limited partner interest in WPZ. Northwest has no employees. Services are provided to Northwest by Williams and its affiliates. Northwest reimburses Williams and its affiliates for the costs of the employees including compensation and employee benefit plan costs and all related administrative costs. In this report, Northwest is at times referred to in the first person as “we,” “us” or “our.” Nature of Operations We own and operate an interstate pipeline system for the mainline transmission of natural gas. This system extends from the San Juan Basin in northwestern New Mexico and southwestern Colorado through Colorado, Utah, Wyoming, Idaho, Oregon and Washington to a point on the Canadian border near Sumas, Washington. Regulatory Accounting We are regulated by the Federal Energy Regulatory Commission (FERC). The Accounting Standards Codification (ASC) Regulated Operations (Topic 980) provides that rate-regulated public utilities account for and report regulatory assets and liabilities consistent with the economic effect of the way in which regulators establish rates if the rates established are designed to recover the costs of providing the regulated service and if the competitive environment makes it probable that such rates can be charged and collected. Accounting for businesses that are regulated and apply the provisions of Topic 980 can differ from the accounting requirements for non-regulated businesses. Transactions that are recorded differently as a result of regulatory accounting requirements include the capitalization of an equity return component on regulated capital projects, capitalization of other project costs, retirements of general plant assets, employee related benefits, environmental costs, negative salvage, asset retirement obligations, and other costs and taxes included in, or expected to be included in, future rates. As a rate-regulated entity, our management has determined that it is appropriate to apply the accounting prescribed by Topic 980, and, accordingly, the accompanying financial statements include the effects of the types of transactions described above that result from regulatory accounting requirements. (See Note 9 for further discussion.) Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Estimates and assumptions which, in the opinion of management, are significant to the underlying amounts included in the financial statements and for which it would be reasonably possible that future events or information could change those estimates include: 1) litigation-related contingencies; 2) environmental remediation obligations; 3) impairment assessments of long-lived assets; 4) depreciation; and 5) asset retirement obligations. Revenue Recognition Our revenues are primarily from services pursuant to long term firm transportation and storage agreements. These agreements provide for a reservation charge based on the volume of contracted capacity and a volumetric charge based on the volume of gas delivered, both at rates specified in our FERC tariffs. We recognize revenues for reservation charges ratably over the contract period regardless of the volume of natural gas that is transported or stored. Revenues for volumetric charges, from both firm and interruptible transportation services and storage injection and withdrawal services, are recognized based on volumes of natural gas scheduled for delivery at the agreed upon delivery point or based on volumes of natural gas scheduled for injection or withdrawal from the storage facility. In the course of providing transportation services to our customers, we may receive or deliver different quantities of gas from shippers than the quantities delivered or received on behalf of those shippers. These transactions result in imbalances, which are typically settled through the receipt or delivery of gas in the future. Customer imbalances to be repaid or recovered in-kind are recorded as exchange gas due from others or due to others in the accompanying balance sheets. The difference between exchange gas due to us from customers and the exchange gas that we owe to customers is included in the exchange gas offset. These imbalances are valued at the average of the spot market rates at the Canadian border and the Rocky Mountain market as published in the SNL Financial “Bidweek Index - Spot Rates.” Settlement of imbalances requires agreement between the pipelines and shippers as to allocations of volumes to specific transportation contracts and timing of delivery of gas based on operational conditions. As a result of the ratemaking process, certain revenues collected by us may be subject to refunds upon the issuance of final orders by the FERC in pending rate proceedings. We record estimates of rate refund liabilities considering our and third-party regulatory proceedings, advice of counsel and other risks. At December 31, 2016 , we had no such rate refund liabilities. Environmental Matters We are subject to federal, state, and local environmental laws and regulations. Environmental expenditures are expensed or capitalized depending on their economic benefit and potential for rate recovery. We believe that expenditures required to meet applicable environmental laws and regulations are prudently incurred in the ordinary course of business and such expenditures would be permitted to be recovered through rates. Property, Plant, and Equipment Property, plant and equipment (plant), consisting principally of natural gas transmission facilities, is recorded at original cost. The FERC identifies installation, construction and replacement costs that are to be capitalized and included in our asset base for recovery in rates. Routine maintenance, repairs, and renewal costs are charged to income as incurred. Gains or losses from the ordinary sale or retirement of plant are charged or credited to accumulated depreciation; certain other gains or losses are recorded in operating income. We provide for depreciation under the composite (group) method at straight-line FERC prescribed rates that are applied to the cost of the group for transmission and storage facilities. Under this method, assets with similar lives and characteristics are grouped and depreciated as one asset. Included in our depreciation rates is a negative salvage component (net cost of removal) that we currently collect in rates. Our depreciation rates are subject to change each time we file a general rate case with the FERC. Depreciation rates used for major regulated gas plant facilities at December 31, 2016 , 2015 , and 2014 are as follows: Category of Property Storage Facilities 1.60 % — 2.76% Transmission Facilities 2.80 % — 6.97% The incrementally priced Evergreen Expansion Project, which was an expansion of our pipeline system, was placed in service on October 1, 2003. The levelized rate design of this project creates a consistent revenue stream over the related 25-year and 15-year customer contract terms. The related levelized depreciation is lower than book depreciation in the early years and higher than book depreciation in the later years of the contract terms. The depreciation component of the levelized incremental rates will equal the accumulated book depreciation by the end of the primary contract terms. The FERC has approved the accounting for the differences between book depreciation and the Evergreen Expansion Project’s levelized depreciation as a regulatory asset. We recorded regulatory debits totaling $3.5 million in 2016 , $2.6 million in 2015 , and $1.5 million in 2014 in the accompanying Statement of Comprehensive Income. These debits relate primarily to the levelized depreciation adjustment for the Evergreen Project discussed above. We record a liability and increase the basis in the underlying asset for the present value of each expected future asset retirement obligation (ARO) at the time the liability is initially incurred, typically when the asset is acquired or constructed. Measurement of AROs includes, as a component of future expected costs, an estimate of the price that a third party would demand, and could expect to receive, for bearing the uncertainties inherent in the obligations, sometimes referred to as market-risk premium. We measure changes in the liability due to passage of time by applying an interest rate to the liability balance. This amount is recognized as an increase in the carrying amount of the liability and is offset by a regulatory asset. The gross regulatory asset balances associated with ARO as of December 31, 2016 and 2015 were $78.5 million and $70.9 million, respectively. The regulatory asset is expected to be fully recovered through the net negative salvage component of depreciation included in our rates; as such, the negative salvage component of accumulated depreciation ($78.5 million and $69.3 million at December 31, 2016 and 2015 , respectively) has been reclassified and netted against the amount of the ARO regulatory asset. Impairment of Long-Lived Assets We evaluate long-lived assets for impairment when events or changes in circumstances indicate, in our management’s judgment, that the carrying value of such assets may not be recoverable. When such a determination has been made, our management’s estimate of undiscounted future cash flows attributable to the assets is compared to the carrying value of the assets to determine whether an impairment has occurred. If an impairment of the carrying value has occurred, the amount of the impairment recognized in the financial statements is determined by estimating the fair value of the assets and recording a loss for the amount that the carrying value exceeds the estimated fair value. Judgments and assumptions are inherent in our management’s estimate of undiscounted future cash flows used to determine recoverability of an asset and the estimate of an asset’s fair value used to calculate the amount of impairment to recognize. The use of alternate judgments and/or assumptions could result in the recognition of different levels of impairment charges in the financial statements. Allowance for Funds Used During Construction Allowance for funds used during construction (AFUDC) represents the estimated cost of borrowed and equity funds applicable to utility plant in process of construction and is included as a cost of property, plant and equipment because it constitutes an actual cost of construction under established regulatory practices. The FERC has prescribed a formula to be used in computing separate allowances for borrowed and equity AFUDC. The allowance for borrowed funds used during construction was $0.4 million for 2016 , $0.5 million for 2015 , and $0.2 million for 2014 . The allowance for equity funds was $1.0 million, $1.1 million, and $0.4 million for 2016 , 2015 , and 2014 , respectively. Both are reflected in Other (Income) and Other Expenses . Income Taxes We generally are not a taxable entity for federal or state and local income tax purposes. The tax on net income is generally borne by unitholders of our ultimate parent, WPZ. Net income for financial statement purposes may differ significantly from taxable income of WPZ’s unitholders as a result of differences between the tax basis and financial reporting basis of assets and liabilities and the taxable income allocation requirements under the WPZ partnership agreement. The aggregated difference in the basis of our assets for financial and tax reporting purposes cannot be readily determined because information regarding each of WPZ’s unitholder’s tax attributes in WPZ is not available to us. Accounts Receivable and Allowance for Doubtful Receivables Accounts receivable are stated at the historical carrying amount net of reserves or write-offs. Our credit risk exposure in the event of nonperformance by the other parties is limited to the face value of the receivables. We perform ongoing credit evaluations of our customers’ financial condition and require collateral from our customers, if necessary. Due to our customer base, we have not historically experienced recurring credit losses in connection with our receivables. Receivables determined to be uncollectible are reserved or written off in the period of determination. Materials and Supplies Inventory All inventories are stated at lower of cost or market. We determine the cost of the inventories using the average cost method. We perform an annual review of materials and supplies inventories, including an analysis of parts that may no longer be useful due to planned replacements of compressor engines and other components on our system. Based on this assessment, we record a reserve for the value of the inventory which can no longer be used for maintenance and repairs on our pipeline. There was a minimal reserve at December 31, 2016 and 2015 . Deferred Charges We amortize deferred charges over varying periods consistent with the FERC approved accounting treatment and recovery for such deferred items. Unamortized debt expense, debt discount and losses on reacquired long-term debt are amortized by the bonds outstanding method over the related debt repayment periods. Contingent Liabilities We record liabilities for estimated loss contingencies, including environmental matters, when we assess that a loss is probable and the amount of the loss can be reasonably estimated. These liabilities are calculated based upon our assumptions and estimates with respect to the likelihood or amount of loss and upon advice of legal counsel, engineers, or other third parties regarding the probable outcomes of the matters. These calculations are made without consideration of any potential recovery from third-parties. We recognize insurance recoveries or reimbursements from others when realizable. Revisions to these liabilities are generally reflected in income when new or different facts or information become known or circumstances change that affect the previous assumptions or estimates. Pension and Other Postretirement Benefits We do not have employees. Certain of the costs charged to us by Williams associated with employees who directly support us include costs related to Williams’ pension and other postretirement benefit plans. (See Note 5 for further discussion.) Although the underlying benefit plans of Williams are single-employer plans, we follow multiemployer plan accounting whereby the amount charged to us, and thus paid by us, is based on our share of net periodic benefit cost. Cash Flows from Operating Activities and Cash Equivalents We use the indirect method to report cash flows from operating activities, which requires adjustments to net income to reconcile to net cash flows provided by operating activities. We include short-term, highly-liquid investments that have an original maturity of three months or less as cash equivalents. Interest Payments Cash payments for interest, net of interest capitalized, were $38.5 million in 2016 , $45.3 million in 2015 , and $44.5 million in 2014 . Accounting Standards Issued But Not Yet Adopted In August 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-15 "Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments" (ASU 2016-15). ASU 2016-15 provides specific guidance on eight cash flow classification issues, including debt prepayment or debt extinguishment costs and distributions received from equity method investees, to reduce diversity in practice. ASU 2016-15 is effective for interim and annual periods beginning after December 15, 2017. Early adoption is permitted. ASU 2016-15 requires a retrospective transition. We are evaluating the impact of ASU 2016-15 on our financial statements. In June 2016, the FASB issued ASU 2016-13 "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments" (ASU 2016-13). ASU 2016-13 changes the impairment model for most financial assets and certain other instruments. For trade and other receivables, held-to-maturity debt securities, loans, and other instruments, entities will be required to use a new forward-looking "expected loss" model that generally will result in the earlier recognition of allowances for losses. The guidance also requires increased disclosures. ASU 2016-13 is effective for interim and annual periods beginning after December 15, 2019. Early adoption is permitted. ASU 2016-13 requires varying transition methods for the different categories of amendments. We do not expect ASU 2016-13 to have a significant impact on our financial statements. In February 2016, the FASB issued ASU 2016-02 "Leases (Topic 842)" (ASU 2016-02). ASU 2016-02 establishes a comprehensive new lease accounting model. ASU 2016-02 clarifies the definition of a lease, requires a dual approach to lease classification similar to current lease classifications, and causes lessees to recognize leases on the balance sheet as a lease liability with a corresponding right-of-use asset. ASU 2016-02 is effective for interim and annual periods beginning after December 15, 2018. Early adoption is permitted. ASU 2016-02 requires a modified retrospective transition for capital or operating leases existing at or entered into after the beginning of the earliest comparative period presented in the financial statements. We are reviewing contracts to identify leases, particularly reviewing the applicability of ASU 2016-02 to contracts involving easements/rights-of-way. In May 2014, the FASB issued ASU 2014-09 establishing Accounting Standards Codification (ASC) Topic 606, "Revenue from Contracts with Customers" (ASC 606). ASC 606 establishes a comprehensive new revenue recognition model designed to depict the transfer of goods or services to a customer in an amount that reflects the consideration the entity expects to be entitled to receive in exchange for those goods or services and requires significantly enhanced revenue disclosures. In August 2015, the FASB issued ASU 2015-14 "Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date" (ASU 2015-14). Per ASU 2015-14, the standard is effective for interim and annual reporting periods beginning after December 15, 2017. ASC 606 allows either full retrospective or modified retrospective transition and early adoption is permitted for annual periods beginning after December 15, 2016. We continue to evaluate the impact the standard may have on our financial statements. For each revenue contract type, we are conducting a formal contract review process to evaluate the impact, if any, that the new revenue standard may have. We have substantially completed that process, but continue to evaluate our accounting for noncash consideration, which exists in contracts where we receive commodities as full or partial consideration, and the accounting for contributions in aid of construction. As such, we are unable to determine the potential impact upon the amount and timing of revenue recognition and related disclosures. Additionally, we have identified possible financial system and internal control changes necessary for adoption. We currently anticipate utilizing a modified retrospective transition upon the adoption of ASC 606 as of January 1, 2018. |
Rate and Regulatory Matters (No
Rate and Regulatory Matters (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Public Utilities, Rate Matters [Abstract] | |
Public Utilities, Disclosure of Rate Matters [Text Block] | RATE AND REGULATORY MATTERS Rates Our rates became effective January 1, 2013, and will remain in effect for 5 years. Rate Case Settlement Filing On January 23, 2017, we filed for FERC approval a Stipulation and Settlement Agreement (Settlement) and were assigned Docket No. RP17-346. The Settlement specified an annual cost of service of $440 million and established a new general system firm Rate Schedule TF-1 (Large Customer) demand rate of $0.39294/Dth with a $0.00832 commodity rate (Phase 1) and a demand rate of $0.39033/Dth with a $0.00832 commodity rate (Phase 2). Phase 1 rates become effective January 1, 2018, with Phase 2 rates becoming effective October 1, 2018. The annual cost of service does not change from Phase 1 to Phase 2, but the Phase 2 rates reflect the termination of fifteen-year levelized contracts that will now become Rate Schedule TF-1 (Large Customer) contracts. Provisions were included in the Settlement that we can file new rates to be effective after October 1, 2018, and that a general rate case filing must be made for rates to become effective no later than January 1, 2023. |
Contingent Liabilities and Comm
Contingent Liabilities and Commitments (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Commitments and Contingencies Disclosure [Abstract] | |
Contingent Liabilities and Commitments | CONTINGENT LIABILITIES AND COMMITMENTS Environmental Matters We are subject to the National Environmental Policy Act and other federal and state legislation regulating the environmental aspects of our business. Except as discussed below, our management believes that we are in substantial compliance with existing environmental requirements. Environmental expenditures are expensed or capitalized depending on their future economic benefit and potential for rate recovery. We believe that, with respect to any expenditures required to meet applicable standards and regulations, the Federal Energy Regulatory Commission (FERC) would grant the requisite rate relief so that substantially all of such expenditures would be permitted to be recovered through rates. Beginning in the mid-1980s, we evaluated many of our facilities for the presence of toxic and hazardous substances to determine to what extent, if any, remediation might be necessary. We identified polychlorinated biphenyl (PCB) contamination in air compressor systems, soils, and related properties at certain compressor station sites. Similarly, we identified hydrocarbon impacts at these facilities due to the former use of earthen pits, lubricating oil leaks or spills, and excess pipe coating released to the environment. In addition, heavy metals have been identified at these sites due to the former use of mercury containing meters and paint and welding rods containing lead, cadmium, and arsenic. The PCBs were remediated pursuant to a Consent Decree with the U.S. Environmental Protection Agency (EPA) in the late 1980s, and we conducted a voluntary clean-up of the hydrocarbon and mercury impacts in the early 1990s. In 2005, the Washington Department of Ecology required us to re-evaluate our previous clean-ups in Washington. During 2006 to 2015, 129 meter stations were evaluated, of which 82 required remediation. As of December 31, 2016 , all of the meter stations have been remediated. Initial assessments have been completed at all thirteen compressor stations in Washington. Additional assessments are ongoing at two of these compressor stations. Remediation has been completed at eleven of the thirteen compressor stations. On the basis of the findings to date, we estimate that environmental assessment and remediation costs will total approximately $4.4 million, measured on an undiscounted basis, and are expected to be incurred through 2020. At December 31, 2016 and 2015 , we had accrued liabilities totaling approximately $4.4 million and $4.6 million, respectively, for these costs. We are conducting environmental assessments and implementing a variety of remedial measures that may result in increases or decreases in the total estimated costs. In March 2008, the EPA promulgated a new, lower National Ambient Air Quality Standard (NAAQS) for ground-level ozone. In May 2012, the EPA completed designation of new eight-hour ozone non-attainment areas. Based on the published designations, no Northwest facilities are located within the non-attainment areas. At this time, it is unknown whether future state regulatory actions associated with implementation of the 2008 ozone standard will impact our operations and increase the cost of additions to property, plant and equipment. Until any additional state regulatory actions are proposed, we are unable to estimate the cost of additions that may be required to meet any such new regulation. In December 2014, the EPA proposed to further reduce the ground-level ozone NAAQS from the March 2008 levels and subsequently finalized a rule on October 1, 2015. We are monitoring the rule's implementation as the reduction will trigger additional federal and state regulatory actions that may impact our operations. As a result, the cost of additions to property, plant, and equipment is expected to increase. We are unable at this time to estimate with any certainty the cost of additions that may be required to meet new regulations. On January 22, 2010, the EPA set a new one-hour nitrogen dioxide (NO 2 ) NAAQS. The effective date of the new NO 2 standard was April 12, 2010. On January 20, 2012, the EPA determined pursuant to available information that no area in the country is violating the 2010 NO 2 NAAQS, and thus, designated all areas of the country as “unclassifiable/attainment.” Also, at that time, the EPA noted its plan to deploy an expanded NO 2 monitoring network beginning in 2013. However, on October 5, 2012, the EPA proposed a graduated implementation of the monitoring network between January 1, 2014 and January 1, 2017. Once three years of data are collected from the new monitoring network, the EPA will reassess attainment status with the one-hour NO 2 NAAQS. Until that time, the EPA or states may require ambient air quality modeling on a case by case basis to demonstrate compliance with the NO 2 standard. Because we are unable to predict the outcome of the EPA’s or states’ future assessment using the new monitoring network, we are unable to estimate the cost of additions that may be required to meet this regulation. Other Matters Various other proceedings are pending against us and are considered incidental to our operations. Summary We estimate that for all matters for which we are able to reasonably estimate a range of loss, including those noted above and others that are not individually significant, our aggregate reasonably possible losses beyond amounts accrued for all of our contingent liabilities are immaterial to our expected future annual results of operations, liquidity and financial position. These calculations have been made without consideration of any potential recovery from third-parties. We have disclosed all significant matters for which we are unable to reasonably estimate a range of possible loss. |
Debt, Financing Arrangements, a
Debt, Financing Arrangements, and Leases (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Debt Disclosure [Abstract] | |
Debt, Financing Arrangements, and Leases | DEBT, FINANCING ARRANGEMENTS, AND LEASES Long-Term Debt Long-term debt, presented net of unamortized discount and unamortized debt issuance costs, consists of the following: December 31, 2016 2015 (Thousands of Dollars) 5.95% senior unsecured notes due 2017 $ 185,000 $ 185,000 6.05% senior unsecured notes due 2018 250,000 250,000 7% senior unsecured notes due 2016 — 175,000 7.125% unsecured debentures due 2025 85,000 85,000 Debt issuance costs (624 ) (1,197 ) Unamortized debt discount (216 ) (383 ) Total long-term debt, including current portion $ 519,160 $ 693,420 Long-term debt due within one year 184,924 174,837 Total long-term debt 334,236 518,583 As of December 31, 2016 , cumulative maturities of outstanding long-term debt (at face value) for the next five years are as follows: (Thousands of Dollars) 2017: 5.95% senior unsecured notes $ 185,000 2018: 6.05% senior unsecured notes 250,000 Total $ 435,000 The long-term debt due within one year at December 31, 2016 is associated with our $185 million 5.95% senior unsecured notes that mature on April 15, 2017. We intend to repay this maturing note by accessing available capacity under our revolving credit facility, advances from our parent, or issuing new long-term debt. The long-term debt due within on year at December 31, 2015 is associated with our $175 million 7% senior unsecured notes that matured on June 15, 2016. In 2006, we entered into certain forward starting interest rate swaps prior to our issuance of the 7% senior unsecured notes due 2016 to hedge the variability of forecasted interest payments arising from changes in interest rates prior to the issuance of this debt. The settlement resulted in a gain, recorded in Accumulated other comprehensive income , that was being amortized to reduce interest expense over the life of the related debt. This was fully amortized in June 2016. Restrictive Debt Covenants At December 31, 2016 , none of our debt instruments restrict the amount of distributions to our parent, provided, however, that under the credit facility described below, we are restricted from making distributions to our parent during an event of default if we have directly incurred indebtedness under the credit facility. Our debt agreements contain restrictions on our ability to incur secured debt beyond certain levels. Retirement of Long-Term Debt In June 2016, we retired our $175.0 million 7 percent senior unsecured notes that matured on June 15, 2016. These notes were retired with proceeds from the repayment of advances to WPZ. Credit Facility On February 2, 2015, we, along with WPZ, Transco, the lenders named therein, and an administrative agent, entered into the Second Amended and Restated Credit Agreement with aggregate commitments available of $3.5 billion, with up to an additional $500 million increase in aggregate commitments available under certain circumstances. The maturity date of the facility is February 2, 2020. However, the co-borrowers may request up to two extensions of the maturity date, each for an additional one-year period, to allow a maturity date as late as February 2, 2022, under certain circumstances. The agreement allows for swing line loans up to an aggregate amount of $150 million, subject to available capacity under the credit facility, and letters of credit commitments available to WPZ of $1.125 billion. We are able to borrow up to $500 million under this credit facility to the extent not otherwise utilized by the other co-borrowers. At December 31, 2016 , no letters of credit have been issued and no loans to WPZ were outstanding under the credit facility. On December 18, 2015, we, along with WPZ, Transco, the lenders named therein, and an administrative agent, entered into the Amendment No. 1 to Second Amended and Restated Credit Agreement modifying the thresholds specified in the covenant related to the maximum ratio of WPZ’s consolidated indebtedness to consolidated EBITDA. Under the credit facility, WPZ is required to maintain a ratio of debt to EBITDA (each as defined in the credit facility) that must be no greater than 5.75 to 1.0 for the quarters ending December 31, 2015, March 31, 2016, and June 30, 2016. The ratio must be no greater than 5.5 to 1.0 for the quarters ending September 30, 2016 and December 31, 2016. The ratio must be no greater than 5.0 to 1.0 for the quarter ending March 31, 2017 and each subsequent fiscal quarter, except for the fiscal quarter and the two following fiscal quarters in which one or more acquisitions have been executed, in which case the ratio must be no greater than 5.50 to 1.0. For us, the ratio of debt to capitalization (defined as net worth plus debt) must be no greater than 65 percent. Measured as of December 31, 2016 , we are in compliance with this financial covenant. Various covenants may limit, among other things, a borrower’s and its material subsidiaries’ ability to grant certain liens supporting indebtedness, a borrower’s ability to merge or consolidate, sell all or substantially all of its assets, enter into certain affiliate transactions, make certain distributions during an event of default, enter into certain restrictive agreements, and allow any material change in the nature of its business. If an event of default with respect to a borrower occurs under the credit facility, the lenders will be able to terminate the commitments for the respective borrowers and accelerate the maturity of any loans of the defaulting borrower under the credit facility agreement and exercise other rights and remedies. Other than swingline loans, each time funds are borrowed, the borrower must choose whether such borrowing will be an alternate base rate borrowing or a Eurodollar borrowing. If such borrowing is an alternate base rate borrowing, interest is calculated on the basis of the greater of (a) the Prime Rate, (b) the Federal Funds Effective Rate plus 1/2 of 1 percent, and (c) a periodic fixed rate equal to the London Interbank Offered Rate (LIBOR) plus 1 percent, plus, in the case of each of (a), (b), and (c), an applicable margin. If the borrowing is a Eurodollar borrowing, interest is calculated on the basis of LIBOR for the relevant period plus an applicable margin. Interest on swingline loans is calculated as the sum of the alternate base rate plus an applicable margin. The borrower is required to pay a commitment fee based on the unused portion of the credit facility. The applicable margin and the commitment fee are determined for each borrower by reference to a pricing schedule based on such borrower’s senior unsecured long-term debt ratings. WPZ participates in a commercial paper program, and WPZ management considers amounts outstanding under this program to be a reduction of available capacity under the credit facility. On February 2, 2015, WPZ amended and restated the commercial paper program for the WPZ/ACMP merger and to allow a maximum outstanding of $3 billion. At December 31, 2016 , WPZ had $93 million in outstanding commercial paper. Leases Our leasing arrangements include mostly premise and equipment leases that are classified as operating leases. Effective October 1, 2009, we entered into an agreement to lease office space from a third party. The agreement has an initial term of approximately 10 years, with an option to renew for an additional 5 or 10 year term. Following are the estimated future minimum annual rental payments required under operating leases, which have initial or remaining noncancelable lease terms in excess of one year: (Thousands of Dollars) 2017 $ 2,758 2018 2,784 2019 2,811 Total $ 8,353 Operating lease rental expense, net of sublease revenues, amounted to $2.7 million, $2.7 million, and $2.5 million for 2016 , 2015 , and 2014 , respectively. |
Benefit Plans (Notes)
Benefit Plans (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Disclosure Text Block [Abstract] | |
Benefit Plans | BENEFIT PLANS Certain of the benefit costs charged to us by Williams associated with employees who directly support us are described below. Additionally, allocated corporate expenses from Williams to us also include amounts related to these same employee benefits, which are not included in the amounts presented below. (See Note 7 for further discussion.) Pension and Other Postretirement Benefit Plans Williams has noncontributory defined benefit pension plans (Williams Pension Plan, Williams Inactive Employees Pension Plan, and The Williams Companies Retirement Restoration Plan) that provide pension benefits for its eligible employees. Pension cost charged to us by Williams was $2.3 million in 2016 , $4.4 million in 2015 , and $4.2 million in 2014 . Williams provides subsidized retiree health care and life insurance benefits to certain eligible participants. Generally, participants that were employed by Williams on or before December 31, 1991 are eligible for subsidized retiree health care benefits. During 2016 , 2015 , and 2014 , we received credits from Williams related to retiree health care and life insurance benefits of $3.8 million, $3.4 million and $4.3 million, respectively. These credits were recorded as regulatory liabilities. We have been allowed by rate case settlements to collect or refund in future rates any differences between the actuarially determined costs and amounts currently being recovered in rates related to other postretirement benefits. Any difference between the annual actuarially determined cost and amounts currently being recovered in rates are recorded as regulatory assets or liabilities and collected or refunded through future rate adjustments. The amount of other postretirement benefits costs deferred as a regulatory liability at December 31, 2016 and 2015 are $30.6 million and $26.8 million, respectively. Defined Contribution Plan Williams maintains a defined contribution plan for substantially all of its employees. Williams charged us compensation expense of $2.2 million in 2016 , $2.2 million in 2015 , and $2.0 million in 2014 for Williams’ company matching contributions to this plan. Employee Stock-Based Compensation Plan Information The Williams Companies, Inc. 2007 Incentive Plan, as subsequently amended and restated (Plan), provides for Williams’ common stock-based awards to both employees and nonmanagement directors. The Plan permits the granting of various types of awards including, but not limited to, restricted stock units and stock options. Awards may be granted for no consideration other than prior and future services or based on certain financial performance targets achieved. Williams currently bills us directly for compensation expense related to stock-based compensation awards based on the fair value of the awards. We are also billed for our proportionate share of Williams’ and other affiliates’ stock-based compensation expense through various allocation processes. Total stock-based compensation expense for the years ended December 31, 2016 , 2015 and 2014 was $1.4 million, $1.5 million and $1.2 million, respectively, excluding amounts allocated from WPZ and Williams. |
Financial Instruments (Notes)
Financial Instruments (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Fair Value Disclosures [Abstract] | |
Financial Instruments | FINANCIAL INSTRUMENTS Fair Value of Financial Instruments The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value: Cash and advances to affiliate —The carrying amounts approximate fair value, because of the short-term nature of these instruments. Long-term debt – The disclosed fair value of our long-term debt, which we consider as a level 2 measurement, is determined by a market approach using broker quoted indicative period-end bond prices. The quoted prices are based on observable transactions in less active markets for our debt or similar instruments. The carrying amount and estimated fair value of our long-term debt, including current maturities, were $519.2 million and $546.8 million, respectively, at December 31, 2016 , and $693.4 million and $721.9 million, respectively, at December 31, 2015 . |
Transactions with Major Custome
Transactions with Major Customers and Affiliates (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Transactions with Major Customers and Affiliates [Abstract] | |
Transactions with Major Customers and Affiliates | TRANSACTIONS WITH MAJOR CUSTOMERS AND AFFILIATES Concentration of Off-Balance-Sheet and Other Credit Risk During the periods presented, more than 10 percent of our operating revenues were generated from each of the following customers: Years Ended December 31, 2016 2015 2014 (Thousands of Dollars) Puget Sound Energy, Inc. $ 120,351 $ 118,384 $ 113,398 Northwest Natural Gas Company 49,895 50,857 50,631 Cascade Natural Gas Corporation 47,951 48,363 (a) (a) Under 10 percent in 2014 . Our major customers are located in the Pacific Northwest. As a general policy, collateral is not required for receivables, but customers’ financial condition and credit worthiness are regularly evaluated and historical collection losses have been minimal. Related Party Transactions We are a participant in WPZ’s cash management program. At December 31, 2016 and 2015 , the advances due to us by WPZ totaled approximately $45.1 million and $171.9 million , respectively. These advances are represented by demand notes and are classified as Current Assets in the accompanying Balance Sheet. The interest rate on these intercompany demand notes is based upon the daily overnight investment rate paid on WPZ’s excess cash at the end of each month, which was approximately 0.39 percent at December 31, 2016 . The interest income from these advances was minimal during the years ended December 31, 2016 , 2015 , and 2014 . Such interest income is included in Other (Income) and Other Expenses: Miscellaneous other (income) expenses, net on the accompanying Statement of Comprehensive Income. We have no employees. Services necessary to operate our business are provided to us by Williams and certain affiliates of Williams. We reimburse Williams and its affiliates for all direct and indirect expenses incurred or payments made (including salary, bonus, incentive compensation, and benefits) in connection with these services. Employees of Williams also provide general administrative and management services to us, and we are charged for certain administrative expenses incurred by Williams. These charges are either directly identifiable or allocated to our assets. Direct charges are for goods and services provided by Williams at our request. Allocated charges are based on a three factor formula, which considers revenues; property, plant, and equipment; and payroll. In management’s estimation, the allocation methodologies used are reasonable and result in a reasonable allocation to us of our costs of doing business incurred by Williams. We were billed $92.8 million, $100.4 million, and $102.4 million in the years ended December 31, 2016 , 2015 , and 2014 , respectively, for these services. Such expenses are primarily included in General and administrative and Operation and maintenance expenses on the accompanying Statement of Comprehensive Income. The amount billed to us during 2016 includes $2.4 million for severance and other related costs associated with a reduction in workforce primarily recognized in the first quarter. In 2015 and 2014 , we incurred reimbursable costs of $0.6 million and $27.3 million, respectively, due from Williams Field Services related to the construction of a natural gas liquids pipeline, of which a minimal amount was outstanding at December 31, 2015. No such costs were incurred or were outstanding at December 31, 2016 . During 2016 , 2015 , and 2014 , we declared and paid cash distributions to our parent of $174.0 million , $168.0 million , and $234.0 million , respectively. During January 2017, we declared and paid cash distributions of $50.0 million to our parent. |
Asset Retirement Obligations (N
Asset Retirement Obligations (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Asset Retirement Obligation Disclosure [Abstract] | |
Asset Retirement Obligations | ASSET RETIREMENT OBLIGATIONS Our accrued asset retirement obligations relate to our gas storage and transmission facilities. At the end of the useful life of our facilities, we are legally obligated to remove certain transmission facilities including underground pipelines, major river spans, compressor stations and meter station facilities. These obligations also include restoration of the property sites after removal of the facilities from above and below the ground. During 2016 and 2015 , our overall asset retirement obligation changed as follows (in thousands): 2016 2015 Beginning balance $ 82,454 $ 94,678 Accretion 7,470 6,870 New obligations 150 2,721 Changes in estimates of existing obligations (1) (29,312 ) (21,815 ) Ending balance $ 60,762 $ 82,454 (1) Changes in estimates of existing obligations are primarily due to the annual review process, which considers various factors including inflation rates, current estimates for removal cost, the estimated remaining life of assets, and discount rates. The decrease in 2016 is primarily attributed to decreases in current estimates for removal costs and inflation rate and an increase in the estimated life of the assets. The decrease in 2015 is primarily attributed to decreases in current estimates for removal costs and inflation rate and an increase in the discount rate. |
Regulatory Assets and Liabiliti
Regulatory Assets and Liabilities (Notes) | 12 Months Ended |
Dec. 31, 2016 | |
Regulatory Assets and Liabilities Disclosure [Abstract] | |
Regulatory Assets and Liabilities | REGULATORY ASSETS AND LIABILITIES Our regulatory assets and liabilities result from our application of the provisions of Topic 980 and are reflected on our balance sheet. Current regulatory assets are included in Exchange gas offset and Prepayments and other . Current regulatory liabilities are included in Exchange gas offset . These balances are presented on our balance sheet on a gross basis and are recoverable or refundable over various periods. Below are the details of our regulatory assets and liabilities as of December 31, 2016 and 2015 : 2016 2015 (Thousands of Dollars) Current regulatory assets: Environmental costs $ — $ 1,300 Levelized depreciation 3,864 2,731 Fuel recovery — 178 Total current regulatory assets 3,864 4,209 Noncurrent regulatory assets: Environmental costs — (1,068 ) Grossed-up deferred taxes on equity funds used during construction 13,051 13,809 Levelized depreciation 21,849 26,493 Asset retirement obligations, net — 1,619 Total noncurrent regulatory assets 34,900 40,853 Total regulatory assets $ 38,764 $ 45,062 Current regulatory liabilities: Fuel recovery $ 1,466 $ — Noncurrent regulatory liabilities: Postretirement benefits 30,587 26,802 Asset retirement obligations, net 130 — Total noncurrent regulatory liabilities 30,717 26,802 Total regulatory liabilities $ 32,183 $ 26,802 The significant regulatory assets and liabilities include: Environmental Costs We have accrued liabilities for assessment and remediation activities to bring certain sites up to current environmental standards. The accrual for these liabilities is offset by a regulatory asset. The regulatory asset is being amortized to expense consistent with amounts collected in rates. Levelized Depreciation Levelized depreciation allows contract revenue streams to remain constant over the primary contract terms by recognizing lower than book depreciation in the early years and higher than book depreciation in later years. The depreciation component of the levelized incremental rates will equal the accumulated book depreciation by the end of the primary contract terms. The difference between levelized depreciation and straight-line book depreciation is recorded as a FERC approved regulatory asset or liability and is eliminated over the levelization period. Grossed-Up Deferred Taxes on Equity Funds Used During Construction The regulatory asset balance was established to offset the deferred tax for the equity component of the allowance for funds used during the construction of long-lived assets. All amounts were generated during the period that we were a taxable entity. Taxes on capitalized funds used during construction and the offsetting deferred income taxes are included in the rate base and are recovered over the depreciable lives of the long-lived asset to which they relate. Asset Retirement Obligations This regulatory asset balance is established to offset depreciation of the ARO asset and changes in the ARO liability due to the passage of time. The regulatory asset is expected to be fully recovered through the net negative salvage component of depreciation included in our rates; as such, the negative salvage component of accumulated depreciation has been reclassified and netted against the amount of the ARO regulatory asset. (See Note 8.) Fuel Recovery These amounts reflect the value of the cumulative volumetric difference between the gas retained from our customers and the gas consumed in operations. These amounts are not included in the rate base, but are expected to be recovered or refunded by changing the fuel reimbursement factor in subsequent fuel filings. Postretirement Benefits We seek to recover the actuarially determined cost of postretirement benefits through rates that are set through periodic general rate filings. Any differences between the annual actuarially determined cost and amounts currently being recovered in rates are recorded as regulatory assets or liabilities and collected or refunded through future rate adjustments. These amounts are not included in the rate base, and we are not currently recovering postretirement benefit costs in our rates. (See Note 5.) |
Summary of Significant Accoun15
Summary of Significant Accounting Policies (Policies) | 12 Months Ended |
Dec. 31, 2016 | |
Organization, Consolidation and Presentation of Financial Statements [Abstract] | |
Regulatory Accounting | Regulatory Accounting We are regulated by the Federal Energy Regulatory Commission (FERC). The Accounting Standards Codification (ASC) Regulated Operations (Topic 980) provides that rate-regulated public utilities account for and report regulatory assets and liabilities consistent with the economic effect of the way in which regulators establish rates if the rates established are designed to recover the costs of providing the regulated service and if the competitive environment makes it probable that such rates can be charged and collected. Accounting for businesses that are regulated and apply the provisions of Topic 980 can differ from the accounting requirements for non-regulated businesses. Transactions that are recorded differently as a result of regulatory accounting requirements include the capitalization of an equity return component on regulated capital projects, capitalization of other project costs, retirements of general plant assets, employee related benefits, environmental costs, negative salvage, asset retirement obligations, and other costs and taxes included in, or expected to be included in, future rates. As a rate-regulated entity, our management has determined that it is appropriate to apply the accounting prescribed by Topic 980, and, accordingly, the accompanying financial statements include the effects of the types of transactions described above that result from regulatory accounting requirements. (See Note 9 for further discussion.) |
Use of Estimates | Use of Estimates The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Estimates and assumptions which, in the opinion of management, are significant to the underlying amounts included in the financial statements and for which it would be reasonably possible that future events or information could change those estimates include: 1) litigation-related contingencies; 2) environmental remediation obligations; 3) impairment assessments of long-lived assets; 4) depreciation; and 5) asset retirement obligations. |
Revenue Recognition | Revenue Recognition Our revenues are primarily from services pursuant to long term firm transportation and storage agreements. These agreements provide for a reservation charge based on the volume of contracted capacity and a volumetric charge based on the volume of gas delivered, both at rates specified in our FERC tariffs. We recognize revenues for reservation charges ratably over the contract period regardless of the volume of natural gas that is transported or stored. Revenues for volumetric charges, from both firm and interruptible transportation services and storage injection and withdrawal services, are recognized based on volumes of natural gas scheduled for delivery at the agreed upon delivery point or based on volumes of natural gas scheduled for injection or withdrawal from the storage facility. In the course of providing transportation services to our customers, we may receive or deliver different quantities of gas from shippers than the quantities delivered or received on behalf of those shippers. These transactions result in imbalances, which are typically settled through the receipt or delivery of gas in the future. Customer imbalances to be repaid or recovered in-kind are recorded as exchange gas due from others or due to others in the accompanying balance sheets. The difference between exchange gas due to us from customers and the exchange gas that we owe to customers is included in the exchange gas offset. These imbalances are valued at the average of the spot market rates at the Canadian border and the Rocky Mountain market as published in the SNL Financial “Bidweek Index - Spot Rates.” Settlement of imbalances requires agreement between the pipelines and shippers as to allocations of volumes to specific transportation contracts and timing of delivery of gas based on operational conditions. As a result of the ratemaking process, certain revenues collected by us may be subject to refunds upon the issuance of final orders by the FERC in pending rate proceedings. We record estimates of rate refund liabilities considering our and third-party regulatory proceedings, advice of counsel and other risks. At December 31, 2016 , we had no such rate refund liabilities. |
Environmental Matters | Environmental Matters We are subject to federal, state, and local environmental laws and regulations. Environmental expenditures are expensed or capitalized depending on their economic benefit and potential for rate recovery. We believe that expenditures required to meet applicable environmental laws and regulations are prudently incurred in the ordinary course of business and such expenditures would be permitted to be recovered through rates. |
Property, Plant, and Equipment | Property, Plant, and Equipment Property, plant and equipment (plant), consisting principally of natural gas transmission facilities, is recorded at original cost. The FERC identifies installation, construction and replacement costs that are to be capitalized and included in our asset base for recovery in rates. Routine maintenance, repairs, and renewal costs are charged to income as incurred. Gains or losses from the ordinary sale or retirement of plant are charged or credited to accumulated depreciation; certain other gains or losses are recorded in operating income. We provide for depreciation under the composite (group) method at straight-line FERC prescribed rates that are applied to the cost of the group for transmission and storage facilities. Under this method, assets with similar lives and characteristics are grouped and depreciated as one asset. Included in our depreciation rates is a negative salvage component (net cost of removal) that we currently collect in rates. Our depreciation rates are subject to change each time we file a general rate case with the FERC. Depreciation rates used for major regulated gas plant facilities at December 31, 2016 , 2015 , and 2014 are as follows: Category of Property Storage Facilities 1.60 % — 2.76% Transmission Facilities 2.80 % — 6.97% The incrementally priced Evergreen Expansion Project, which was an expansion of our pipeline system, was placed in service on October 1, 2003. The levelized rate design of this project creates a consistent revenue stream over the related 25-year and 15-year customer contract terms. The related levelized depreciation is lower than book depreciation in the early years and higher than book depreciation in the later years of the contract terms. The depreciation component of the levelized incremental rates will equal the accumulated book depreciation by the end of the primary contract terms. The FERC has approved the accounting for the differences between book depreciation and the Evergreen Expansion Project’s levelized depreciation as a regulatory asset. We recorded regulatory debits totaling $3.5 million in 2016 , $2.6 million in 2015 , and $1.5 million in 2014 in the accompanying Statement of Comprehensive Income. These debits relate primarily to the levelized depreciation adjustment for the Evergreen Project discussed above. We record a liability and increase the basis in the underlying asset for the present value of each expected future asset retirement obligation (ARO) at the time the liability is initially incurred, typically when the asset is acquired or constructed. Measurement of AROs includes, as a component of future expected costs, an estimate of the price that a third party would demand, and could expect to receive, for bearing the uncertainties inherent in the obligations, sometimes referred to as market-risk premium. We measure changes in the liability due to passage of time by applying an interest rate to the liability balance. This amount is recognized as an increase in the carrying amount of the liability and is offset by a regulatory asset. The gross regulatory asset balances associated with ARO as of December 31, 2016 and 2015 were $78.5 million and $70.9 million, respectively. The regulatory asset is expected to be fully recovered through the net negative salvage component of depreciation included in our rates; as such, the negative salvage component of accumulated depreciation ($78.5 million and $69.3 million at December 31, 2016 and 2015 , respectively) has been reclassified and netted against the amount of the ARO regulatory asset. |
Impairment of Long-Lived Assets | Impairment of Long-Lived Assets We evaluate long-lived assets for impairment when events or changes in circumstances indicate, in our management’s judgment, that the carrying value of such assets may not be recoverable. When such a determination has been made, our management’s estimate of undiscounted future cash flows attributable to the assets is compared to the carrying value of the assets to determine whether an impairment has occurred. If an impairment of the carrying value has occurred, the amount of the impairment recognized in the financial statements is determined by estimating the fair value of the assets and recording a loss for the amount that the carrying value exceeds the estimated fair value. Judgments and assumptions are inherent in our management’s estimate of undiscounted future cash flows used to determine recoverability of an asset and the estimate of an asset’s fair value used to calculate the amount of impairment to recognize. The use of alternate judgments and/or assumptions could result in the recognition of different levels of impairment charges in the financial statements. |
Allowance for Funds Used During Construction | Allowance for Funds Used During Construction Allowance for funds used during construction (AFUDC) represents the estimated cost of borrowed and equity funds applicable to utility plant in process of construction and is included as a cost of property, plant and equipment because it constitutes an actual cost of construction under established regulatory practices. The FERC has prescribed a formula to be used in computing separate allowances for borrowed and equity AFUDC. The allowance for borrowed funds used during construction was $0.4 million for 2016 , $0.5 million for 2015 , and $0.2 million for 2014 . The allowance for equity funds was $1.0 million, $1.1 million, and $0.4 million for 2016 , 2015 , and 2014 , respectively. Both are reflected in Other (Income) and Other Expenses . |
Income Taxes | Income Taxes We generally are not a taxable entity for federal or state and local income tax purposes. The tax on net income is generally borne by unitholders of our ultimate parent, WPZ. Net income for financial statement purposes may differ significantly from taxable income of WPZ’s unitholders as a result of differences between the tax basis and financial reporting basis of assets and liabilities and the taxable income allocation requirements under the WPZ partnership agreement. The aggregated difference in the basis of our assets for financial and tax reporting purposes cannot be readily determined because information regarding each of WPZ’s unitholder’s tax attributes in WPZ is not available to us. |
Accounts Receivable and Allowance for Doubtful Receivables | Accounts Receivable and Allowance for Doubtful Receivables Accounts receivable are stated at the historical carrying amount net of reserves or write-offs. Our credit risk exposure in the event of nonperformance by the other parties is limited to the face value of the receivables. We perform ongoing credit evaluations of our customers’ financial condition and require collateral from our customers, if necessary. Due to our customer base, we have not historically experienced recurring credit losses in connection with our receivables. Receivables determined to be uncollectible are reserved or written off in the period of determination. |
Materials and Supplies Inventory | Materials and Supplies Inventory All inventories are stated at lower of cost or market. We determine the cost of the inventories using the average cost method. We perform an annual review of materials and supplies inventories, including an analysis of parts that may no longer be useful due to planned replacements of compressor engines and other components on our system. Based on this assessment, we record a reserve for the value of the inventory which can no longer be used for maintenance and repairs on our pipeline. There was a minimal reserve at December 31, 2016 and 2015 . |
Deferred Charges | Deferred Charges We amortize deferred charges over varying periods consistent with the FERC approved accounting treatment and recovery for such deferred items. Unamortized debt expense, debt discount and losses on reacquired long-term debt are amortized by the bonds outstanding method over the related debt repayment periods. |
Contingent Liabilities | Contingent Liabilities We record liabilities for estimated loss contingencies, including environmental matters, when we assess that a loss is probable and the amount of the loss can be reasonably estimated. These liabilities are calculated based upon our assumptions and estimates with respect to the likelihood or amount of loss and upon advice of legal counsel, engineers, or other third parties regarding the probable outcomes of the matters. These calculations are made without consideration of any potential recovery from third-parties. We recognize insurance recoveries or reimbursements from others when realizable. Revisions to these liabilities are generally reflected in income when new or different facts or information become known or circumstances change that affect the previous assumptions or estimates. |
Pension and Other Postretirement Benefits | Pension and Other Postretirement Benefits We do not have employees. Certain of the costs charged to us by Williams associated with employees who directly support us include costs related to Williams’ pension and other postretirement benefit plans. (See Note 5 for further discussion.) Although the underlying benefit plans of Williams are single-employer plans, we follow multiemployer plan accounting whereby the amount charged to us, and thus paid by us, is based on our share of net periodic benefit cost. |
Cash Equivalents | We include short-term, highly-liquid investments that have an original maturity of three months or less as cash equivalents. |
Financial Instruments (Policies
Financial Instruments (Policies) | 12 Months Ended |
Dec. 31, 2016 | |
Fair Value Disclosures [Abstract] | |
Fair value of financial instruments | Fair Value of Financial Instruments The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value: Cash and advances to affiliate —The carrying amounts approximate fair value, because of the short-term nature of these instruments. Long-term debt – The disclosed fair value of our long-term debt, which we consider as a level 2 measurement, is determined by a market approach using broker quoted indicative period-end bond prices. The quoted prices are based on observable transactions in less active markets for our debt or similar instruments. The carrying amount and estimated fair value of our long-term debt, including current maturities, were $519.2 million and $546.8 million, respectively, at December 31, 2016 , and $693.4 million and $721.9 million, respectively, at December 31, 2015 . |
Summary of Significant Accoun17
Summary of Significant Accounting Policies (Tables) | 12 Months Ended |
Dec. 31, 2016 | |
Organization, Consolidation and Presentation of Financial Statements [Abstract] | |
Depreciation rates | We provide for depreciation under the composite (group) method at straight-line FERC prescribed rates that are applied to the cost of the group for transmission and storage facilities. Under this method, assets with similar lives and characteristics are grouped and depreciated as one asset. Included in our depreciation rates is a negative salvage component (net cost of removal) that we currently collect in rates. Our depreciation rates are subject to change each time we file a general rate case with the FERC. Depreciation rates used for major regulated gas plant facilities at December 31, 2016 , 2015 , and 2014 are as follows: Category of Property Storage Facilities 1.60 % — 2.76% Transmission Facilities 2.80 % — 6.97% |
Debt, Financing Arrangements,18
Debt, Financing Arrangements, and Leases (Tables) | 12 Months Ended |
Dec. 31, 2016 | |
Debt Disclosure [Abstract] | |
Long-term debt instruments | Long-term debt, presented net of unamortized discount and unamortized debt issuance costs, consists of the following: December 31, 2016 2015 (Thousands of Dollars) 5.95% senior unsecured notes due 2017 $ 185,000 $ 185,000 6.05% senior unsecured notes due 2018 250,000 250,000 7% senior unsecured notes due 2016 — 175,000 7.125% unsecured debentures due 2025 85,000 85,000 Debt issuance costs (624 ) (1,197 ) Unamortized debt discount (216 ) (383 ) Total long-term debt, including current portion $ 519,160 $ 693,420 Long-term debt due within one year 184,924 174,837 Total long-term debt 334,236 518,583 |
Maturities of long-term debt | As of December 31, 2016 , cumulative maturities of outstanding long-term debt (at face value) for the next five years are as follows: (Thousands of Dollars) 2017: 5.95% senior unsecured notes $ 185,000 2018: 6.05% senior unsecured notes 250,000 Total $ 435,000 |
Future minimum annual rental payments | Following are the estimated future minimum annual rental payments required under operating leases, which have initial or remaining noncancelable lease terms in excess of one year: (Thousands of Dollars) 2017 $ 2,758 2018 2,784 2019 2,811 Total $ 8,353 |
Transactions with Major Custo19
Transactions with Major Customers and Affiliates (Tables) | 12 Months Ended |
Dec. 31, 2016 | |
Transactions with Major Customers and Affiliates [Abstract] | |
Schedule of revenue by major customers | During the periods presented, more than 10 percent of our operating revenues were generated from each of the following customers: Years Ended December 31, 2016 2015 2014 (Thousands of Dollars) Puget Sound Energy, Inc. $ 120,351 $ 118,384 $ 113,398 Northwest Natural Gas Company 49,895 50,857 50,631 Cascade Natural Gas Corporation 47,951 48,363 (a) (a) Under 10 percent in 2014 . |
Asset Retirement Obligations (T
Asset Retirement Obligations (Tables) | 12 Months Ended |
Dec. 31, 2016 | |
Asset Retirement Obligation Disclosure [Abstract] | |
Schedule of change in asset retirement obligation | During 2016 and 2015 , our overall asset retirement obligation changed as follows (in thousands): 2016 2015 Beginning balance $ 82,454 $ 94,678 Accretion 7,470 6,870 New obligations 150 2,721 Changes in estimates of existing obligations (1) (29,312 ) (21,815 ) Ending balance $ 60,762 $ 82,454 (1) Changes in estimates of existing obligations are primarily due to the annual review process, which considers various factors including inflation rates, current estimates for removal cost, the estimated remaining life of assets, and discount rates. The decrease in 2016 is primarily attributed to decreases in current estimates for removal costs and inflation rate and an increase in the estimated life of the assets. The decrease in 2015 is primarily attributed to decreases in current estimates for removal costs and inflation rate and an increase in the discount rate. |
Regulatory Assets and Liabili21
Regulatory Assets and Liabilities (Tables) | 12 Months Ended |
Dec. 31, 2016 | |
Regulatory Assets and Liabilities Disclosure [Abstract] | |
Schedule of Regulatory Assets and Liabilities [Table Text Block] | Our regulatory assets and liabilities result from our application of the provisions of Topic 980 and are reflected on our balance sheet. Current regulatory assets are included in Exchange gas offset and Prepayments and other . Current regulatory liabilities are included in Exchange gas offset . These balances are presented on our balance sheet on a gross basis and are recoverable or refundable over various periods. Below are the details of our regulatory assets and liabilities as of December 31, 2016 and 2015 : 2016 2015 (Thousands of Dollars) Current regulatory assets: Environmental costs $ — $ 1,300 Levelized depreciation 3,864 2,731 Fuel recovery — 178 Total current regulatory assets 3,864 4,209 Noncurrent regulatory assets: Environmental costs — (1,068 ) Grossed-up deferred taxes on equity funds used during construction 13,051 13,809 Levelized depreciation 21,849 26,493 Asset retirement obligations, net — 1,619 Total noncurrent regulatory assets 34,900 40,853 Total regulatory assets $ 38,764 $ 45,062 Current regulatory liabilities: Fuel recovery $ 1,466 $ — Noncurrent regulatory liabilities: Postretirement benefits 30,587 26,802 Asset retirement obligations, net 130 — Total noncurrent regulatory liabilities 30,717 26,802 Total regulatory liabilities $ 32,183 $ 26,802 |
Summary of Significant Accoun22
Summary of Significant Accounting Policies (Details) | 1 Months Ended | 12 Months Ended | ||
Jan. 31, 2017 | Dec. 31, 2016USD ($)employee | Dec. 31, 2015USD ($) | Dec. 31, 2014USD ($) | |
Subsidiary of Limited Liability Company or Limited Partnership [Line Items] | ||||
Parent, total ownership percentage | 60.00% | |||
Parent, limited partner ownership percentage | 58.00% | |||
Parent, general partner ownership percentage | 2.00% | |||
Entity number of employees | employee | 0 | |||
Revenue Recognition [Abstract] | ||||
Reserve for rate refund, Current | $ 0 | |||
Reserve for rate refund, Noncurrent | 0 | |||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Regulatory debits | 3,510,000 | $ 2,550,000 | $ 1,487,000 | |
Regulatory assets | 34,900,000 | 40,853,000 | ||
Capitalized Interest Costs, Including Allowance for Funds Used During Construction [Abstract] | ||||
Allowance for funds used during construction, debt | 400,000 | 500,000 | 200,000 | |
Allowance for funds used during construction, equity | 953,000 | 1,099,000 | 391,000 | |
Interest Payments [Abstract] | ||||
Cash payments for interest, net of interest capitalized | 38,500,000 | 45,300,000 | 44,500,000 | |
Levelized depreciation [Member] | ||||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Regulatory debits | 3,500,000 | 2,600,000 | $ 1,500,000 | |
Regulatory assets | 21,849,000 | 26,493,000 | ||
Asset retirement obligation [Member] | ||||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Regulatory assets | 78,500,000 | 70,900,000 | ||
Negative salvage [Member] | ||||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Regulatory assets | $ (78,500,000) | $ (69,300,000) | ||
Financial Repositioning [Member] | Subsequent Event [Member] | ||||
Subsidiary of Limited Liability Company or Limited Partnership [Line Items] | ||||
Parent, limited partner ownership percentage | 74.00% | |||
Parent, general partner ownership percentage | 2.00% | |||
Storage Facilities [Member] | Minimum [Member] | ||||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Depreciaton rates | 1.60% | 1.60% | 1.60% | |
Storage Facilities [Member] | Maximum [Member] | ||||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Depreciaton rates | 2.76% | 2.76% | 2.76% | |
Transmission Facilities [Member] | Minimum [Member] | ||||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Depreciaton rates | 2.80% | 2.80% | 2.80% | |
Transmission Facilities [Member] | Maximum [Member] | ||||
Public Utility, Property, Plant and Equipment [Line Items] | ||||
Depreciaton rates | 6.97% | 6.97% | 6.97% |
Rate and Regulatory Matters (De
Rate and Regulatory Matters (Details) $ in Thousands | Oct. 01, 2018$ / dekatherm | Jan. 01, 2018$ / dekatherm | Jan. 23, 2017USD ($) | Dec. 31, 2016 |
Public Utilities, General Disclosures [Line Items] | ||||
Duration of effective period of rates | 5 years | |||
Subsequent Event [Member] | ||||
Public Utilities, General Disclosures [Line Items] | ||||
Annual Cost of Service Pending | $ | $ 440,000 | |||
Subsequent Event [Member] | Phase 1 Demand Rate per Dth Pending | ||||
Public Utilities, General Disclosures [Line Items] | ||||
Demand Rate Pending | 0.39294 | |||
Subsequent Event [Member] | Phase 1 Commodity Rate Pending | ||||
Public Utilities, General Disclosures [Line Items] | ||||
Commodity Rate Pending | 0.00832 | |||
Subsequent Event [Member] | Phase 2 Demand Rate per Dth Pending | ||||
Public Utilities, General Disclosures [Line Items] | ||||
Demand Rate Pending | 0.39033 | |||
Subsequent Event [Member] | Phase 2 Commodity Rate Pending | ||||
Public Utilities, General Disclosures [Line Items] | ||||
Commodity Rate Pending | 0.00832 |
Contingent Liabilities and Co24
Contingent Liabilities and Commitments (Details) - USD ($) $ in Millions | Dec. 31, 2016 | Dec. 31, 2015 |
Environmental Matters | ||
Environmental assessment and remediation costs, undiscounted | $ 4.4 | |
Accrued environmental liabilities | $ 4.4 | $ 4.6 |
Debt, Financing Arrangements,25
Debt, Financing Arrangements, and Leases (Details) | Dec. 18, 2015 | Feb. 02, 2015USD ($) | Oct. 02, 2009 | Jun. 30, 2016USD ($) | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) | Dec. 31, 2014USD ($) |
Debt Instrument [Line Items] | |||||||
Debt issuance costs | $ (624,000) | $ (1,197,000) | |||||
Unamortized debt discount | (216,000) | (383,000) | |||||
Total long-term debt, including current portion | 519,160,000 | 693,420,000 | |||||
Long-term debt due within one year | 184,924,000 | 174,837,000 | |||||
Total long-term debt | 334,236,000 | 518,583,000 | |||||
Maturities of long-term debt | |||||||
2017: 5.95% senior unsecured notes | 185,000,000 | ||||||
2018: 6.05% senior unsecured notes | 250,000,000 | ||||||
Total | 435,000,000 | ||||||
Extinguishment of Debt [Line Items] | |||||||
Retirement of Long-Term Debt | $ 175,000,000 | ||||||
Line of Credit Facility [Line Items] | |||||||
Lease, initial term | 10 years | ||||||
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] | |||||||
2,017 | 2,758,000 | ||||||
2,018 | 2,784,000 | ||||||
2,019 | 2,811,000 | ||||||
Total | 8,353,000 | ||||||
Operating Leases, Rent Expense, Net [Abstract] | |||||||
Operating lease rent expense, net of sublease revenues | 2,700,000 | 2,700,000 | $ 2,500,000 | ||||
Minimum [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Lease, renewal term | 5 years | ||||||
Maximum [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Lease, renewal term | 10 years | ||||||
Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Line of credit facility, maximum borrowing capacity | $ 3,500,000,000 | ||||||
Additional amount by which credit facility can be increased | 500,000,000 | ||||||
Line of credit facility, remaining borrowing capacity | $ 500,000,000 | ||||||
Maximum Ratio Of Debt To Capitalization | 65.00% | ||||||
Commercial paper | 93,000,000 | ||||||
Williams Partners L.P. [Member] | Rate addition to federal funds effective rate [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Line of credit facility, basis spread on variable rate | 0.50% | ||||||
Williams Partners L.P. [Member] | Rate addition to London interbank offered rate (LIBOR) [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Line of credit facility, basis spread on variable rate | 1.00% | ||||||
$3.5 billion credit facility | Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Letters of credit outstanding, amount | 0 | ||||||
Line of credit facility, amount outstanding | 0 | ||||||
Swing Line Advances [Member] | Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Line of credit facility, maximum borrowing capacity | $ 150,000,000 | ||||||
Letter of credit [Member] | Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Line of credit facility, maximum borrowing capacity | 1,125,000,000 | ||||||
Commercial paper [Member] | Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Line of credit facility, maximum borrowing capacity | $ 3,000,000,000 | ||||||
Dec 2015, Mar & Jun 2016 [Member] | Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Maximum ratio of debt to EBITDA | 5.75 | ||||||
Sep & Dec 2016 [Member] | Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Maximum ratio of debt to EBITDA | 5.5 | ||||||
Mar 2017 & Subsequent Quarters [Member] | Williams Partners L.P. [Member] | |||||||
Line of Credit Facility [Line Items] | |||||||
Maximum ratio of debt to EBITDA | 5 | ||||||
Debt to EBITDA, after acquisitions, ratio | 5.5 | ||||||
5.95% senior unsecured notes due 2017 [Member] | |||||||
Debt Instrument [Line Items] | |||||||
Long-term debt | 185,000,000 | 185,000,000 | |||||
Long-term debt due within one year | $ 184,924,000 | ||||||
Interest rate stated percentage | 5.95% | ||||||
6.05% senior unsecured notes due 2018 [Member] | |||||||
Debt Instrument [Line Items] | |||||||
Long-term debt | $ 250,000,000 | 250,000,000 | |||||
7% senior unsecured notes due 2016 [Member] | |||||||
Debt Instrument [Line Items] | |||||||
Long-term debt | 0 | 175,000,000 | |||||
Long-term debt due within one year | $ 174,837,000 | ||||||
Interest rate stated percentage | 7.00% | 7.00% | |||||
7.125% unsecured debentures due 2025 [Member] | |||||||
Debt Instrument [Line Items] | |||||||
Long-term debt | $ 85,000,000 | $ 85,000,000 |
Benefit Plans (Details)
Benefit Plans (Details) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014 | |
Salaries, Wages and Officers' Compensation [Abstract] | |||
Stock-based compensation expense | $ 1,400 | $ 1,500 | $ 1,200 |
Defined Benefit Plan Disclosure [Line Items] | |||
Pension cost | 2,300 | 4,400 | 4,200 |
Regulatory liabilities | 30,717 | 26,802 | |
Defined contribution plan matching contributions expense | 2,200 | 2,200 | 2,000 |
Retiree health care and life insurance benefits [Member] | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Regulatory liabilities | 3,800 | 3,400 | $ 4,300 |
Other Postretirement Benefit Costs | |||
Defined Benefit Plan Disclosure [Line Items] | |||
Regulatory liabilities | $ 30,587 | $ 26,802 |
Financial Instruments (Details)
Financial Instruments (Details) - USD ($) $ in Millions | Dec. 31, 2016 | Dec. 31, 2015 |
Carrying amount [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Long-term debt, including current maturities | $ 519.2 | $ 693.4 |
Estimate of fair value [Member] | Fair Value, Inputs, Level 2 [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Long-term debt, including current maturities | $ 546.8 | $ 721.9 |
Transactions with Major Custo28
Transactions with Major Customers and Affiliates (Details) $ in Thousands | 1 Months Ended | 12 Months Ended | ||
Jan. 31, 2017USD ($) | Dec. 31, 2016USD ($)employee | Dec. 31, 2015USD ($) | Dec. 31, 2014USD ($) | |
Related Party Transaction [Line Items] | ||||
Advances to affiliate | $ 45,137 | $ 171,867 | ||
Related party transaction, rate | 0.39% | |||
Entity number of employees | employee | 0 | |||
Related party transaction, expenses from transactions with related party | $ 92,800 | 100,400 | $ 102,400 | |
Severance Costs | 2,400 | |||
Cash distributions to parent | 174,000 | 168,000 | 234,000 | |
Williams Field Services [Member] | ||||
Related Party Transaction [Line Items] | ||||
Reimbursable costs | 0 | 600 | 27,300 | |
Williams Partners L.P. [Member] | ||||
Related Party Transaction [Line Items] | ||||
Advances to affiliate | 45,100 | 171,900 | ||
Subsequent Event [Member] | ||||
Related Party Transaction [Line Items] | ||||
Cash distributions to parent | $ 50,000 | |||
Puget Sound Energy, Inc. [Member] | ||||
Revenue, Major Customer [Line Items] | ||||
Operating revenues | 120,351 | 118,384 | 113,398 | |
Northwest Natural Gas Company [Member] | ||||
Revenue, Major Customer [Line Items] | ||||
Operating revenues | 49,895 | 50,857 | $ 50,631 | |
Cascade Natural Gas Corporation [Member] | ||||
Revenue, Major Customer [Line Items] | ||||
Operating revenues | $ 47,951 | $ 48,363 |
Asset Retirement Obligations (D
Asset Retirement Obligations (Details) - USD ($) $ in Thousands | 12 Months Ended | |
Dec. 31, 2016 | Dec. 31, 2015 | |
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward] | ||
Beginning balance | $ 82,454 | $ 94,678 |
Accretion | 7,470 | 6,870 |
New obligations | 150 | 2,721 |
Changes in estimates of existing obligations (1) | (29,312) | (21,815) |
Ending balance | $ 60,762 | $ 82,454 |
Regulatory Assets and Liabili30
Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2016 | Dec. 31, 2015 |
Regulatory Assets [Line Items] | ||
Current regulatory assets | $ 3,864 | $ 4,209 |
Noncurrent regulatory assets | 34,900 | 40,853 |
Total regulatory assets | 38,764 | 45,062 |
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 30,717 | 26,802 |
Total regulatory liabilities | 32,183 | 26,802 |
Fuel recovery [Member] | ||
Regulatory Liabilities [Line Items] | ||
Current regulatory liabilities | 1,466 | 0 |
Postretirement benefits [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 30,587 | 26,802 |
Asset retirement obligations, net [Member] | ||
Regulatory Liabilities [Line Items] | ||
Regulatory liabilities | 130 | 0 |
Environmental costs [Member] | ||
Regulatory Assets [Line Items] | ||
Current regulatory assets | 0 | 1,300 |
Noncurrent regulatory assets | 0 | (1,068) |
Levelized depreciation [Member] | ||
Regulatory Assets [Line Items] | ||
Current regulatory assets | 3,864 | 2,731 |
Noncurrent regulatory assets | 21,849 | 26,493 |
Fuel Recovery [Member] | ||
Regulatory Assets [Line Items] | ||
Current regulatory assets | 0 | 178 |
Grossed-up deferred taxes on equity funds used during construction [Member] | ||
Regulatory Assets [Line Items] | ||
Noncurrent regulatory assets | 13,051 | 13,809 |
Asset retirement obligations, net [Member] | ||
Regulatory Assets [Line Items] | ||
Noncurrent regulatory assets | $ 0 | $ 1,619 |