Leases - Schedule of Components of Lease Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lease Cost [Line Items]
Net lease cost	$ 3,439	$ 2,611	$ 10,268	$ 8,167
Other, net [Member]
Lease Cost [Line Items]
Operating lease cost for subleased/assigned properties	609	707	1,780	1,863
Sublease income subleased/assigned properties	(605)	(707)	(1,776)	(1,863)
Occupancy [Member]
Lease Cost [Line Items]
Operating lease cost	3,432	2,602	10,238	8,003
Variable lease costs	$ 3	$ 9	$ 26	$ 164