DERIVATIVE INSTRUMENTS - Schedule of Gross and Net Amounts of Recognized Derivative Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Derivative Assets
Gross Amounts of Recognized Assets	$ 18,233	$ 44,421
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	18,233	44,421
Collateral Received	0	0
Net Amount	18,233	44,421
Derivative Liabilities
Gross Amounts of Recognized Liabilities	35,557	7,581
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	35,557	7,581
Collateral Pledged	16,877	309
Net Amount	18,680	7,272
Derivative instruments not designated as hedges
Derivative Assets
Gross Amounts of Recognized Assets	16,579	44,421
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	16,579	44,421
Collateral Received	0	0
Net Amount	16,579	44,421
Derivative Liabilities
Gross Amounts of Recognized Liabilities	35,496	6,388
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	35,496	6,388
Collateral Pledged	16,877	309
Net Amount	18,619	6,079
Derivative instruments not designated as hedges | Interest rate futures
Derivative Assets
Gross Amounts of Recognized Assets	6,819	387
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	6,819	387
Collateral Received	0	0
Net Amount	6,819	387
Derivative Liabilities
Gross Amounts of Recognized Liabilities	7,139	1,685
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	7,139	1,685
Collateral Pledged	6,984	209
Net Amount	155	1,476
Derivative instruments not designated as hedges | Foreign currency forward contracts, underwriting and non-investment operations
Derivative Assets
Gross Amounts of Recognized Assets	1,745	31,755
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	1,745	31,755
Collateral Received	0	0
Net Amount	1,745	31,755
Derivative Liabilities
Gross Amounts of Recognized Liabilities	17,956	1,160
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	17,956	1,160
Collateral Pledged	0	0
Net Amount	17,956	1,160
Derivative instruments not designated as hedges | Foreign currency forward contracts, investment operations
Derivative Assets
Gross Amounts of Recognized Assets	4,365	11,866
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	4,365	11,866
Collateral Received	0	0
Net Amount	4,365	11,866
Derivative Liabilities
Gross Amounts of Recognized Liabilities	508	2,165
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	508	2,165
Collateral Pledged	0	0
Net Amount	508	2,165
Derivative instruments not designated as hedges | Credit default swaps
Derivative Assets
Gross Amounts of Recognized Assets	3,650	413
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	3,650	413
Collateral Received	0	0
Net Amount	3,650	413
Derivative Liabilities
Gross Amounts of Recognized Liabilities	9,893	1,055
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	9,893	1,055
Collateral Pledged	9,893	100
Net Amount	0	955
Derivative instruments not designated as hedges | Equity futures
Derivative Liabilities
Gross Amounts of Recognized Liabilities		323
Gross Amounts Offset in the Balance Sheet		0
Net Amounts of Liabilities Presented in the Balance Sheet		323
Collateral Pledged		0
Net Amount		323
Derivative instruments designated as hedges | Foreign currency forward contracts, investment operations
Derivative Assets
Gross Amounts of Recognized Assets	1,654
Gross Amounts Offset in the Balance Sheet	0
Net Amounts of Assets Presented in the Balance Sheet	1,654
Collateral Received	0
Net Amount	1,654
Derivative Liabilities
Gross Amounts of Recognized Liabilities	61	1,193
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	61	1,193
Collateral Pledged	0	0
Net Amount	$ 61	$ 1,193