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, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Schedule Of Equity Method Investments [Line Items]
Total income	$ 125,926	$ 101,504	$ 252,966	$ 196,378
Net (loss) income	(8,542)	3,830	(5,751)	10,675
Balance sheet:
Total assets	1,280,703		1,280,703		$ 1,176,857
Total liabilities	948,805		948,805		762,399
Limited Partnership [Member]
Schedule Of Equity Method Investments [Line Items]
Total income	179,117	384,629	515,945	373,681
Total expenses	(23,023)	(25,208)	(72,340)	(80,720)
Net (loss) income	156,094	$ 359,421	443,605	$ 292,961
Balance sheet:
Total assets	5,899,813		5,899,813		5,855,616
Total liabilities	$ 408,725		$ 408,725		$ 564,732