Other Assets and Liabilities - Summary Of Current Expected Credit Loss Reserve By Pool (Detail) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Current Expected Credit Loss Reserve	$ 5,122,000	$ 0
Increase (Decrease) in current expected credit loss reserve	(1,003,000)	3,674,000
Current Expected Credit Loss Reserve	4,119,000	4,119,000
U.S. Loans [Member]
Current Expected Credit Loss Reserve	5,122,000	0
Increase (Decrease) in current expected credit loss reserve	(1,003,000)	3,674,000
Current Expected Credit Loss Reserve	4,119,000	4,119,000
Non-U.S. Loans [Member]
Current Expected Credit Loss Reserve	0	0
Increase (Decrease) in current expected credit loss reserve	0	0
Current Expected Credit Loss Reserve	0	0
Unique Loans [Member]
Current Expected Credit Loss Reserve	0	0
Increase (Decrease) in current expected credit loss reserve	0	0
Current Expected Credit Loss Reserve	0	0
Impaired Loans [Member]
Current Expected Credit Loss Reserve	0	0
Increase (Decrease) in current expected credit loss reserve		0
Current Expected Credit Loss Reserve	0	0
Accounting Standards Update 2016-13 [Member]
Current Expected Credit Loss Reserve		445,000
Current Expected Credit Loss Reserve	$ 445,000	445,000
Accounting Standards Update 2016-13 [Member] | U.S. Loans [Member]
Current Expected Credit Loss Reserve		445,000
Accounting Standards Update 2016-13 [Member] | Non-U.S. Loans [Member]
Current Expected Credit Loss Reserve		0
Accounting Standards Update 2016-13 [Member] | Unique Loans [Member]
Current Expected Credit Loss Reserve		0
Accounting Standards Update 2016-13 [Member] | Impaired Loans [Member]
Current Expected Credit Loss Reserve		$ 0