Cover
Cover - USD ($) | 12 Months Ended | ||
Dec. 31, 2020 | Feb. 23, 2021 | Jun. 30, 2020 | |
Cover [Abstract] | |||
Document Type | 10-K/A | ||
Document Annual Report | true | ||
Document Period End Date | Dec. 31, 2020 | ||
Current Fiscal Year End Date | --12-31 | ||
Document Transition Report | false | ||
Entity File Number | 001-36777 | ||
Entity Registrant Name | JAMES RIVER GROUP HOLDINGS, LTD. | ||
Entity Incorporation, State or Country Code | D0 | ||
Entity Well-known Seasoned Issuer | Yes | ||
Entity Common Stock, Shares Outstanding | 30,765,510 | ||
Amendment Flag | false | ||
Document Fiscal Period Focus | FY | ||
Document Fiscal Year Focus | 2020 | ||
Entity Tax Identification Number | 98-0585280 | ||
Entity Address, Address Line Three | Wellesley House | ||
Entity Address, Address Line Two | 2nd Floor | ||
Entity Address, Address Line One | 90 Pitts Bay Road | ||
Entity Address, City or Town | Pembroke | ||
Entity Address, Postal Zip Code | HM08 | ||
Entity Address, Country | BM | ||
City Area Code | 441 | ||
Local Phone Number | 278-4580 | ||
Title of 12(b) Security | Common Shares, par value $0.0002 per share | ||
Trading Symbol | JRVR | ||
Security Exchange Name | NASDAQ | ||
Entity Interactive Data Current | Yes | ||
Entity Voluntary Filers | No | ||
Entity Current Reporting Status | Yes | ||
Entity Filer Category | Large Accelerated Filer | ||
Entity Small Business | false | ||
Entity Emerging Growth Company | false | ||
Entity Shell Company | false | ||
ICFR Auditor Attestation Flag | true | ||
Entity Public Float | $ 1,332,336,690 | ||
Entity Central Index Key | 0001620459 | ||
Document Information [Line Items] | |||
Document Period End Date | Dec. 31, 2020 | ||
Current Fiscal Year End Date | --12-31 |