Commitments and Contingencies (Reserve for Unfunded Commitments) (Detail) - SEC Schedule, 12-09, Allowance, Credit Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance, beginning of period	$ 13,104	$ 12,755
ACL assumed from Sterling	6,749	0
(Benefit) provision for credit losses	(213)	45
Balance, end of period	$ 19,640	$ 12,800