Fair Value Measurements - Schedule of Classification of Investments and Certain Other Assets and Liabilities Measured at Fair Value on Recurring Basis and Investments Measured at NAV (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	$ 683,496	$ 991,089
Derivative Assets	14,554	922
Total investments measured at fair value	698,050	992,011
Securities sold, not yet purchased	4,651	6,828
Derivative Liabilities	327,160	372,245
Total of Liabilities Measured at Fair Value	331,811	379,073
Level 1 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total investments measured at fair value	599,110	919,083
Securities sold, not yet purchased	4,651	6,828
Derivative Liabilities	115	10,005
Total of Liabilities Measured at Fair Value	4,766	16,833
Level 2 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative Assets	$ 14,554	$ 922
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other assets	Other assets
Total investments measured at fair value	$ 14,554	$ 922
Derivative Liabilities	327,045	362,240
Total of Liabilities Measured at Fair Value	327,045	362,240
Level 3 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total investments measured at fair value	19,418	871
NAV [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total investments measured at fair value	64,968	71,135
Equities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	43,889	54,040
Equities [Member] | Level 1 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	43,243	53,462
Equities [Member] | Level 3 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	646	578
Alternative Investment Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	56,947	49,757
Alternative Investment Funds [Member] | Level 1 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	27,073	24,972
Alternative Investment Funds [Member] | NAV [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	29,874	24,785
Debt Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	178,556	164,952
Debt Funds [Member] | Level 1 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	178,552	164,947
Debt Funds [Member] | NAV [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	4	5
Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	350,282	375,761
Equity Funds [Member] | Level 1 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	350,242	375,712
Equity Funds [Member] | NAV [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	40	49
Private Equity Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	53,822	46,589
Private Equity Funds [Member] | Level 3 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	18,772	293
Private Equity Funds [Member] | NAV [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value	$ 35,050	46,296
Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value		299,990
Debt [Member] | Level 1 [Member] | Fair Value, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments at fair value		$ 299,990