Accounting Policies

No definition available.

Name:	jrvr_AccountingPoliciesLineItems
Namespace Prefix:	jrvr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents number of insurance companies owned by the entity.

+ References

No definition available.

+ Details

Name:	jrvr_NumberOfInsuranceCompanies
Namespace Prefix:	jrvr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482685/740-10-50-12

+ Details

Name:	us-gaap_EffectiveIncomeTaxRateContinuingOperations
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481203/810-10-50-4

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481203/810-10-50-6

+ Details

Name:	us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	srt_StatementGeographicalAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Accounting Policies - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
Accounting Policies - Narrative (Details) $ in Millions	Jun. 30, 2023 USD ($) insurance_company	Jun. 30, 2022	Jun. 30, 2023 USD ($) insurance_company	Jun. 30, 2022	Dec. 31, 2022 USD ($)
Accounting Policies [Line Items]
Investment in variable interest entities \| $	$ 8.8		$ 8.8		$ 9.2
Effective U.S. federal income tax expense (benefit) rate	23.60%	25.30%	23.90%	24.90%
UNITED STATES
Accounting Policies [Line Items]
Number of insurance companies \| insurance_company	5		5