Investments - Summary of Unaudited Financial Information and Unaudited Financial Position of Limited Partnerships (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Schedule Of Equity Method Investments [Line Items]
Total income	$ 206,245	$ 127,327	$ 412,859	$ 256,356
Net income	57,099	14,882	114,055	32,675
Balance sheet:
Total assets	1,911,381		1,911,381		$ 1,811,316
Total liabilities	1,457,347		1,457,347		1,387,991
Limited Partnership [Member]
Schedule Of Equity Method Investments [Line Items]
Total income	16,173	(144,193)	19,239	38,167
Total expenses	(17,675)	(24,840)	(43,276)	(27,097)
Net income	(1,502)	$ (169,033)	(24,037)	$ 11,070
Balance sheet:
Total assets	4,101,810		4,101,810		4,072,501
Total liabilities	$ 202,337		$ 202,337		$ 220,525