v3.26.1
Fair Value Measurements - Narrative (Details) - security
Mar. 31, 2026
Dec. 31, 2025
Dec. 31, 2024
Fair Value Disclosures [Abstract]
Number of equity securities held
1
1
1
X
- Definition
Number Of Equity Securities Held
+ References
No definition available.
+ Details
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jrvr_NumberOfEquitySecuritiesHeld
Namespace Prefix:
jrvr_
Data Type:
xbrli:integerItemType
Balance Type:
na
Period Type:
instant
X
- References
No definition available.
+ Details
Name:
us-gaap_FairValueDisclosuresAbstract
Namespace Prefix:
us-gaap_
Data Type:
xbrli:stringItemType
Balance Type:
na
Period Type:
duration