v3.26.3
DERIVATIVE INSTRUMENTS - Schedule of Derivative Contracts (Details) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Interest rate futures | Derivative instruments not designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount $ 7,796,245 $ 7,575,688
Interest rate futures | Derivative instruments not designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount 2,729,364 4,179,575
Interest rate swaps | Derivative instruments not designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount 2,050 0
Interest rate swaps | Derivative instruments not designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount 31,380 29,600
Foreign currency forward contracts, underwriting and non-investment operations | Derivative instruments not designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount 1,158,175 1,102,740
Foreign currency forward contracts, underwriting and non-investment operations | Derivative instruments not designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount 235,742 412,005
Foreign currency forward contracts, investment operations | Derivative instruments not designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount 242,882 159,267
Foreign currency forward contracts, investment operations | Derivative instruments not designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount 142,638 186,854
Foreign currency forward contracts, investment operations | Derivative instruments designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount 0 0
Foreign currency forward contracts, investment operations | Derivative instruments designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount 68,891 64,142
Credit default swaps | Derivative instruments not designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount 8,935 39,500
Credit default swaps | Derivative instruments not designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount 1,565,176 847,864
Equity futures | Derivative instruments not designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount 1,543,605 1,729,226
Equity futures | Derivative instruments not designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount 0 0
Commodity futures | Derivative instruments not designated as hedges | Long    
Derivative [Line Items]    
Derivative, notional amount 729,742 1,189,027
Commodity futures | Derivative instruments not designated as hedges | Short    
Derivative [Line Items]    
Derivative, notional amount $ 0 $ 0