Employee Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Deferral percentage of base salary (up to)	80.00%
Deferral percentage of other compensation (up to)	100.00%
Employee deferrals deemed vested percentage upon contribution	100.00%
Company's contributions to the plan	$ 3.2	$ 2.5	$ 1.6