Stockholders' Equity - Summary of Status of Stock Incentive Plans and Changes During Periods (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended			84 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
Number of Options
Beginning balance (in shares)	259,969	329,872	434,401
Options granted (in shares)	0	0	0	0
Awards exercised (in shares)	(14,002)	(16,878)	(55,382)
Options forfeited (in shares)	(136,351)	(53,024)	(49,147)
Ending balance (in shares)	109,616	259,969	329,872	109,616
Number of options exercisable (in shares)	109,616	259,969	329,872	109,616
Weighted Average Exercise Price
Beginning balance (in dollars per share)	$ 34.68	$ 33.65	$ 30.04
Options granted (in dollars per share)	0.00	0.00	0.00
Awards exercised (in dollars per share)	6.99	7.00	3.29
Options forfeited (in dollars per share)	35.24	37.09	35.97
Ending balance (in dollars per share)	37.52	34.68	33.65	$ 37.52
Weighted average exercise price exercisable (in dollars per share)	$ 37.52	$ 34.68	$ 33.65	$ 37.52
Weighted Average Contractual Life and Aggregate Intrinsic Value
Weighted average contractual life outstanding	5 days	6 months 10 days	1 year 3 months 20 days
Weighted average contractual life exercisable	5 days	6 months 10 days	1 year 3 months 20 days
Aggregate intrinsic value outstanding	$ 0	$ 246	$ 359	$ 0
Aggregate intrinsic value exercisable	$ 0	$ 246	$ 359	$ 0