Employee Benefit Plans - Schedule of Stock Options Outstanding and Exercisable (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares, Options outstanding, beginning balance	315	12	566
Shares outstanding, Options forfeited and expired			(124)
Shares outstanding, Options exercised	165	115	442
Shares, Options outstanding, ending balance	150	315	12
Weighted average exercise price, Options outstanding, beginning balance	$ 13.86	$ 10.77	$ 13.67
Shares outstanding, Options vested and expected to vest, ending balance	150
Weighted average exercise price, Options forfeited and expired			15.35
Shares outstanding, Options exercisable, ending balance	150
Weighted average exercise price, Options exercised	$ 12.45	11.64	13.20
Weighted average exercise price, Options outstanding, ending balance	15.43	$ 13.86	$ 10.77
Weighted average exercise price, Options vested and expected to vest, ending balance	15.43
Weighted average exercise price, Options exercisable, ending balance	$ 15.43
Weighted average remaining contractual term (years), Options outstanding	1 year 3 months 8 days	1 year 5 months 16 days
Weighted average remaining contractual term (years), Options vested and expected to vest	1 year 3 months 8 days
Weighted average remaining contractual term (years), Options exercisable	1 year 3 months 8 days
Aggregate intrinsic value, Options outstanding	$ 2,116	$ 9,480
Aggregate intrinsic value, Options vested and expected to vest	2,116
Aggregate intrinsic value, Options exercisable	$ 2,116