DERIVATIVE INSTRUMENTS - Gain (Loss) Recognized in the Consolidated Statements of Operations Related to its Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	$ 14,175	$ (66,348)
Derivative instruments not designated as hedges
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	13,227	(63,321)
Derivative instruments not designated as hedges | Interest rate futures
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	25,483	(28,787)
Derivative instruments not designated as hedges | Foreign currency forward contracts, underwriting and non-investment operations
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	4,745	(21,142)
Derivative instruments not designated as hedges | Foreign currency forward contracts, investment operations
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	(3,680)	(1,891)
Derivative instruments not designated as hedges | Credit default swaps
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	(11,954)	(4,137)
Derivative instruments not designated as hedges | Equity futures
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized on derivatives	(1,367)	(7,364)
Derivative instruments designated as hedges | Foreign currency forward contracts, investment operations
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive income (loss)	$ 948	$ (3,027)