Stockholders' Equity - Summary of Stock Appreciation Rights Activity (Detail) (Stock appreciation rights [Member], USD $)	6 Months Ended
	Jun. 30, 2014
Stock appreciation rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock appreciation rights, Outstanding at December 31, 2013	806,116
Number of stock appreciation rights, Granted
Number of stock appreciation rights, Exercised
Number of stock appreciation rights, Forfeited
Number of stock appreciation rights, Outstanding at June 30, 2014	806,116
Number of stock appreciation rights, Vested and exercisable at June 30, 2014	500,767
Weighted Average Exercise Price, Outstanding at December 31, 2013	$ 23.98
Weighted Average Exercise Price, Granted
Weighted Average Exercise Price, Exercised
Weighted Average Exercise Price, Forfeited
Weighted Average Exercise Price, Outstanding at June 30, 2014	$ 23.98
Weighted Average Exercise Price, Vested and exercisable at June 30, 2014	$ 23.98
Weighted Average Remaining Contractual Term (in years), Outstanding at June 30, 2014	7 years 4 months 17 days
Weighted Average Remaining Contractual Term (in years), Vested and exercisable at June 30, 2014	7 years 3 months 26 days
Aggregate Intrinsic Value, Outstanding at June 30, 2014	$ 42.8
Aggregate Intrinsic Value, Vested and exercisable at June 30, 2014	$ 26.6