Leases - Schedule of Quantitative Information Related to Leases (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lease expenses
Fixed lease expenses - operating	[1]	$ 3,059	$ 3,046	$ 9,323	$ 9,751
Variable lease expenses - operating	[1]	1,204	2,196	4,746	6,830
Sublease income	[1]	(494)	(1,075)	(1,845)	(3,332)
Total lease expenses	[1]	3,769	4,167	12,224	13,249
Other information
Gross operating cash flows for operating leases	[2]	(5,063)	(7,400)	(17,183)	(25,503)
Operating cash flows from subleases	[2]	$ 486	$ 1,112	$ 1,720	$ 3,417
Weighted average remaining lease term (in months) - operating leases		71 months	79 months	71 months	79 months
Weighted average discount rate - operating leases		4.90%	5.20%	4.90%	5.20%

[1] Lease expense and sublease income represent the amount recorded within our unaudited condensed consolidated statements of income. Variable lease amounts represent expenses recognized as incurred which are not included in the lease liability. Fixed lease expenses and sublease income are recorded on a straight-line basis over the lease term and therefore are not necessarily representative of cash payments during the same period.

[2] Cash flows are presented on a consolidated basis and represent cash payments for fixed and variable lease costs.