Other Assets and Liabilities - Summary of Unfunded Loan Commitement (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019
CECL reserve	$ 178,050	$ 178,050	$ 112,694		$ 0
(Decrease) Increase in CECL reserve	65,356	164,108
U.S. Loans [Member]
CECL reserve	61,404	61,404	64,861		0
(Decrease) Increase in CECL reserve	(3,457)	52,449
Non-U.S. Loans [Member]
CECL reserve	19,745	19,745	21,825		0
(Decrease) Increase in CECL reserve	(2,080)	16,114
Unfunded Loan Commitment [Member]
CECL reserve	15,002	15,002	22,536		0
(Decrease) Increase in CECL reserve	(7,534)	11,739
Unfunded Loan Commitment [Member] | U.S. Loans [Member]
CECL reserve	12,836	12,836	19,793		0
(Decrease) Increase in CECL reserve	(6,957)	10,035
Unfunded Loan Commitment [Member] | Non-U.S. Loans [Member]
CECL reserve	2,078	2,078	2,672		0
(Decrease) Increase in CECL reserve	(594)	1,625
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	3,300		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	27,240	27,240	26,008		0
(Decrease) Increase in CECL reserve	1,232	25,884
Unique Loans [Member] | Unfunded Loan Commitment [Member]
CECL reserve	88	88	71		0
(Decrease) Increase in CECL reserve	17	79
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	69,661	$ 0		$ 0
(Decrease) Increase in CECL reserve	69,661	69,661
Impaired Loans [Member] | Unfunded Loan Commitment [Member]
CECL reserve	0	0
(Decrease) Increase in CECL reserve	$ 0	$ 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