Equity-Based Compensation - Schedule of Activity Related to Stock Option Awards (Detail)	9 Months Ended
	Sep. 30, 2017 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options, Outstanding, Beginning Balance | shares	3,441,900
Options, Forfeited | shares	(353,449)
Options, Expired | shares	(43,592)
Options, Exercised | shares	(590)
Options, Outstanding, Ending Balance | shares	3,044,269
Options, Exercisable at September 30, 2017 | shares	1,262,329
Weighted Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 18.67
Weighted Average Exercise Price, Forfeited | $ / shares	17.98
Weighted Average Exercise Price, Expired | $ / shares	18.81
Weighted Average Exercise Price, Exercised | $ / shares	18.67
Weighted Average Exercise Price, Outstanding, Ending Balance | $ / shares	18.75
Weighted Average Exercise Price, Exercisable at September 30, 2017 | $ / shares	$ 18.95
Weighted Average Remaining Contractual Life, Outstanding at September 30, 2017	7 years 10 months 24 days
Weighted Average Remaining Contractual Life, Exercisable at September 30, 2017	7 years 9 months 11 days