DERIVATIVE INSTRUMENTS - Consolidated Balance Sheets and Fair Value of the Principal Derivative Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Derivative Assets
Gross Amounts of Recognized Assets	$ 25,307	$ 44,421
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	25,307	44,421
Collateral Received	0	0
Net Amount	25,307	44,421
Derivative Liabilities
Gross Amounts of Recognized Liabilities	14,989	7,581
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	14,989	7,581
Collateral Pledged	7,896	309
Net Amount	7,093	7,272
Derivative instruments not designated as hedges
Derivative Assets
Gross Amounts of Recognized Assets	24,688	44,421
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	24,688	44,421
Collateral Received	0	0
Net Amount	24,688	44,421
Derivative Liabilities
Gross Amounts of Recognized Liabilities	14,989	6,388
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	14,989	6,388
Collateral Pledged	7,896	309
Net Amount	7,093	6,079
Derivative instruments not designated as hedges | Interest rate futures
Derivative Assets
Gross Amounts of Recognized Assets	370	387
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	370	387
Collateral Received	0	0
Net Amount	370	387
Derivative Liabilities
Gross Amounts of Recognized Liabilities	2,113	1,685
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	2,113	1,685
Collateral Pledged	2,045	209
Net Amount	68	1,476
Derivative instruments not designated as hedges | Foreign Currency Forward Contracts, Underwriting and Non-investment Operations
Derivative Assets
Gross Amounts of Recognized Assets	24,119	31,755
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	24,119	31,755
Collateral Received	0	0
Net Amount	24,119	31,755
Derivative Liabilities
Gross Amounts of Recognized Liabilities	4,027	1,160
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	4,027	1,160
Collateral Pledged	0	0
Net Amount	4,027	1,160
Derivative instruments not designated as hedges | Foreign currency forward contracts, investment operations
Derivative Assets
Gross Amounts of Recognized Assets	78	11,866
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	78	11,866
Collateral Received	0	0
Net Amount	78	11,866
Derivative Liabilities
Gross Amounts of Recognized Liabilities	2,998	2,165
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	2,998	2,165
Collateral Pledged	0	0
Net Amount	2,998	2,165
Derivative instruments not designated as hedges | Credit default swaps
Derivative Assets
Gross Amounts of Recognized Assets	121	413
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Assets Presented in the Balance Sheet	121	413
Collateral Received	0	0
Net Amount	121	413
Derivative Liabilities
Gross Amounts of Recognized Liabilities	5,851	1,055
Gross Amounts Offset in the Balance Sheet	0	0
Net Amounts of Liabilities Presented in the Balance Sheet	5,851	1,055
Collateral Pledged	5,851	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	619
Gross Amounts Offset in the Balance Sheet	0
Net Amounts of Assets Presented in the Balance Sheet	619
Collateral Received	0
Net Amount	$ 619
Derivative Liabilities
Gross Amounts of Recognized Liabilities		1,193
Gross Amounts Offset in the Balance Sheet		0
Net Amounts of Liabilities Presented in the Balance Sheet		1,193
Collateral Pledged		0
Net Amount		$ 1,193