Equity-Based Compensation - Schedule of Activity Related to Stock Option Awards (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options, Outstanding, Beginning Balance | shares	2,923,448
Options, Forfeited | shares	(323,903)
Options, Expired | shares	(33,641)
Options, Exercised | shares	(484)
Options, Outstanding, Ending Balance | shares	2,565,420
Options, Exercisable at March 31, 2017 | shares	2,094,948
Weighted Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 18.78
Weighted Average Exercise Price, Forfeited | $ / shares	18.11
Weighted Average Exercise Price, Expired | $ / shares	18.65
Weighted Average Exercise Price, Exercised | $ / shares	14.17
Weighted Average Exercise Price, Outstanding, Ending Balance | $ / shares	18.86
Weighted Average Exercise Price, Exercisable at March 31, 2017 | $ / shares	$ 19.14
Weighted Average Remaining Contractual Life, Outstanding at March 31, 2017	7 years 4 months 2 days
Weighted Average Remaining Contractual Life, Exercisable at March 31, 2017	7 years 2 months 26 days
Aggregate Intrinsic Value, Outstanding at March 31, 2017 | $	$ 57
Aggregate Intrinsic Value, Exercisable at March 31, 2017 | $	$ 15