Stock-Based Compensation Plans and Employee Benefits - Summary of Stock Option Activity (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 Sharebased Payments [Abstract]
Number of Options Outstanding, Beginning Balance	1,806	2,812	2,961
Number of Options, Granted	154	633	557
Number of Options, Exercised	(52)	(855)	(234)
Number of Options, Forfeited	(731)	(784)	(472)
Number of Options Outstanding, Ending Balance	1,177	1,806	2,812
Number of Options exercisable	795	1,038	1,760
Weighted Average Exercise Price, Beginning balance	$ 19.16	$ 20.29	$ 22.48
Weighted Average Exercise Price, Granted	14.43	16.74	19.26
Weighted Average Exercise Price, Exercised	7.33	11.62	12.85
Weighted Average Exercise Price, Forfeited	22.31	29.46	36.51
Weighted Average Exercise Price, Ending balance	17.11	19.16	20.29
Weighted Average Exercise Price, Options exercisable	$ 17.46	$ 20.49	$ 21.69
Weighted-Average Remaining Contractual Term (Years), Ending Balance	5 years 7 months 6 days
Weighted-Average Remaining Contractual Term (Years), Options exercisable	4 years 6 months	4 years 6 months	4 years 2 months 12 days
Aggregate Intrinsic Value, Ending balance	$ 196
Aggregate Intrinsic Value, Options exercisable	$ 196	$ 1,608	$ 6,764