Leases - (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Lease terms
Option to extend			20
Weighted-average remaining lease term	9 years		9 years		10 years
Weighted-average discount rate	4.90%		4.90%		4.90%
Increase in Right-of-Use Asset				$ 96,790
Lease expense
Operating lease expense	$ 6,397	$ 5,418	$ 12,793	10,645
Variable lease expense	1,336	1,129	2,628	2,302
Rent expense	$ 7,733	$ 6,547	$ 15,421	$ 12,947
Minimum
Lease terms
Remaining lease terms	1 year		1 year
Maximum
Lease terms
Remaining lease terms	10 years		10 years