Other Assets and Liabilities - Summary of Unfunded Loan Commitement (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
CECL reserve	$ 173,549		$ 0
(Decrease) Increase in CECL reserve	159,607
U.S. Loans [Member]
CECL reserve	42,995		0
(Decrease) Increase in CECL reserve	34,040
Non-U.S. Loans [Member]
CECL reserve	27,734		0
(Decrease) Increase in CECL reserve	24,103
Unfunded Loan Commitment [Member]
CECL reserve	10,031		0
(Decrease) Increase in CECL reserve	6,768
Unfunded Loan Commitment [Member] | U.S. Loans [Member]
CECL reserve	6,953		0
(Decrease) Increase in CECL reserve	4,152
Unfunded Loan Commitment [Member] | Non-U.S. Loans [Member]
CECL reserve	2,994		0
(Decrease) Increase in CECL reserve	2,541
Accounting Standards Update 2016-13 [Member]
CECL reserve		$ 13,942
Accounting Standards Update 2016-13 [Member] | U.S. Loans [Member]
CECL reserve		8,955
Accounting Standards Update 2016-13 [Member] | Non-U.S. Loans [Member]
CECL reserve		3,631
Accounting Standards Update 2016-13 [Member] | Unfunded Loan Commitment [Member]
CECL reserve	3,300	3,263
Accounting Standards Update 2016-13 [Member] | Unfunded Loan Commitment [Member] | U.S. Loans [Member]
CECL reserve		2,801
Accounting Standards Update 2016-13 [Member] | Unfunded Loan Commitment [Member] | Non-U.S. Loans [Member]
CECL reserve		453
Unique Loans [Member]
CECL reserve	33,159		0
(Decrease) Increase in CECL reserve	31,803
Unique Loans [Member] | Unfunded Loan Commitment [Member]
CECL reserve	84		0
(Decrease) Increase in CECL reserve	75
Unique Loans [Member] | Accounting Standards Update 2016-13 [Member]
CECL reserve		1,356
Unique Loans [Member] | Accounting Standards Update 2016-13 [Member] | Unfunded Loan Commitment [Member]
CECL reserve		9
Impaired Loans [Member]
CECL reserve	69,661		0
(Decrease) Increase in CECL reserve	69,661
Impaired Loans [Member] | Unfunded Loan Commitment [Member]
CECL reserve	0		$ 0
(Decrease) Increase in CECL reserve	$ 0
Impaired Loans [Member] | Accounting Standards Update 2016-13 [Member]
CECL reserve		0
Impaired Loans [Member] | Accounting Standards Update 2016-13 [Member] | Unfunded Loan Commitment [Member]
CECL reserve		$ 0