Leases - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Lease Cost [Line Items]
Net lease cost	$ 3,266	$ 3,439	$ 9,937	$ 10,268
Other, net [Member]
Lease Cost [Line Items]
Operating lease cost for subleased/assigned properties	507	609	1,548	1,780
Sublease income subleased/assigned properties	(512)	(605)	(1,559)	(1,776)
Occupancy [Member]
Lease Cost [Line Items]
Operating lease cost	3,269	3,432	9,939	10,238
Variable lease costs	$ 2	$ 3	$ 9	$ 26