Stock-Based Compensation - Option Activity (Detail) - Stock Option [Member] - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares
Outstanding, Beginning Balance	678	1,085	1,316
Options granted	8	27	31
Options exercised	(29)	(170)	(155)
Options canceled/forfeited	(88)	(264)	(107)
Outstanding, Ending Balance	569	678	1,085
Options exercisable	198
Shares available for future grant	1,884
Weighted Average Exercise Price
Outstanding, Beginning Balance	$ 14.90	$ 12.86	$ 12.81
Options granted	11.33	13.03	17.26
Options exercised	10.16	7.56	13.12
Options canceled/forfeited	17.20	11.06	13.06
Outstanding, Ending Balance	14.74	$ 14.90	$ 12.86
Options exercisable	$ 15.67
Weighted Average Remaining Contractual Life
Outstanding, contractual life (in years)	3 years 8 months 16 days
Options exercisable (in years)	2 years 7 months 24 days
Aggregate Intrinsic Value
Outstanding intrinsic value	$ 80
Options exercisable	$ 0