Other Assets and Liabilities - Summary Of Current Expected Credit Loss Reserve By Pool (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Current Expected Credit Loss Reserve	$ 122	$ 889	$ 1,723	$ 4,119	$ 5,122	$ 0	$ 1,723	$ 0
Increase (Decrease) in current expected credit loss reserve	158	(767)	(834)	(2,086)	(1,003)	4,677
Current Expected Credit Loss Reserve	$ 280	$ 122	$ 889	$ 2,033	$ 4,119	5,122	$ 280	2,033
Accounting Standards Update 2016-13 [Member]
Current Expected Credit Loss Reserve						$ 445		$ 445