Loans Receivable, Net - Schedule Of Current Expected Credit Loss Reserve By Pool (Detail) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
Loans Receivable, Net
CECL reserve	$ 130,388	$ 128,945	$ 172,100	$ 177,026	$ 178,050	$ 112,694	$ 173,549		$ 0
Increase (decrease) in CECL reserve	98,752	(43,155)	(1,449)	(1,024)	65,356	1,443
U.S. Loans [Member]
Loans Receivable, Net
CECL reserve	20,926	17,673	44,534	50,642	61,404	64,861	42,995
Increase (decrease) in CECL reserve	55,906	(26,861)	1,539	(10,762)	(3,457)	3,253
Non-U.S. Loans [Member]
Loans Receivable, Net
CECL reserve	8,546	8,829	24,600	26,780	19,745	21,825	27,734
Increase (decrease) in CECL reserve	18,194	(15,771)	(3,134)	7,035	(2,080)	(283)
Unique Loans [Member]
Loans Receivable, Net
CECL reserve	31,255	32,782	33,305	29,943	27,240	26,008	33,159		0
Increase (decrease) in CECL reserve	24,652	(523)	146	2,703	1,232	(1,527)
Impaired Loans [Member]
Loans Receivable, Net
CECL reserve	69,661	69,661	69,661	69,661	69,661	0	$ 69,661		$ 0
Increase (decrease) in CECL reserve	$ 0	$ 0	$ 0	$ 0	$ 69,661	$ 0
Accounting Standards Update 2016-13 [Member]
Loans Receivable, Net
CECL reserve								$ 13,942
Accounting Standards Update 2016-13 [Member] | U.S. Loans [Member]
Loans Receivable, Net
CECL reserve								8,955
Accounting Standards Update 2016-13 [Member] | Non-U.S. Loans [Member]
Loans Receivable, Net
CECL reserve								3,631
Accounting Standards Update 2016-13 [Member] | Unique Loans [Member]
Loans Receivable, Net
CECL reserve								1,356
Accounting Standards Update 2016-13 [Member] | Impaired Loans [Member]
Loans Receivable, Net
CECL reserve								$ 0