Equity-based Compensation - Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares outstanding, Beginning Balance	562,025
Number of shares, Granted	732,000
Number of shares, Exercised
Number of shares, Forfeited	(24,705)
Number of shares outstanding, Ending Balance	1,269,320	562,025
Number of shares, Exercisable	696,037
Weighted-average exercise price, Outstanding, Beginning of Period	$ 18.50
Weighted-average exercise price, Granted	$ 4.96
Weighted-average exercise price, Exercised
Weighted-average exercise price, Forfeited	$ 14.82
Weighted-average exercise price, Outstanding, End of Period	$ 10.78	$ 18.50
Weighted-average exercise price, Exercisable	$ 15.48
Weighted-average remaining contractual term (in years), Outstanding	7 years 8 months 12 days	7 years
Weighted-average remaining contractual term (in years), Exercisable	7 years 2 months 12 days
Aggregate intrinsic value, Outstanding, Beginning
Aggregate intrinsic value, Outstanding, Ending	89
Aggregate intrinsic value, Exercisable	$ 23