Stock-based Compensation - Summary of Stock Appreciation Rights (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Time-Based Stock Appreciation Rights [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance	3,789,394
Number of Shares, Granted	90,000	0
Number of Shares, Exercised	(46,500)
Number of Shares, Outstanding, Ending Balance	3,832,894
Number of Shares, Exercisable	3,706,527
Number of Shares, Vested and expected to vest	3,832,894
Weighted-Average Exercise Price, Outstanding, Beginning Balance	$ 5.23
Weighted-Average Exercise Price, Granted	8.58
Weighted-Average Exercise Price, Exercised	4.18
Weighted-Average Exercise Price, Outstanding, Ending Balance	5.25
Weighted-Average Exercise Price, Exercisable	5.17
Weighted-Average Exercise Price, Vested and expected to vest	$ 5.25
Weighted-Average Remaining Contractual Term, Outstanding	4 years 4 months 10 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 1 month 13 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	4 years 4 months 10 days
Aggregate Intrinsic Value, Outstanding, Ending balance	$ 18,389
Aggregate Intrinsic Value, Exercisable	18,448
Aggregate Intrinsic Value, Vested and expected to vest	$ 18,389
Performance-Based Stock Appreciation Rights [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance	589,424
Number of Shares, Granted		0
Number of Shares, Exercised	(6,800)
Number of Shares, Forfeited or expired	(44,611)
Number of Shares, Outstanding, Ending Balance	538,013
Number of Shares, Exercisable	538,013
Number of Shares, Vested and expected to vest	538,013
Weighted-Average Exercise Price, Outstanding, Beginning Balance	$ 6.06
Weighted-Average Exercise Price, Exercised	3.06
Weighted-Average Exercise Price, Forfeited or expired	11.00
Weighted-Average Exercise Price, Outstanding, Ending Balance	5.85
Weighted-Average Exercise Price, Exercisable	5.85
Weighted-Average Exercise Price, Vested and expected to vest	$ 5.85
Weighted-Average Remaining Contractual Term, Outstanding	4 years 5 months 16 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 5 months 16 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	4 years 5 months 16 days
Aggregate Intrinsic Value, Outstanding, Ending balance	$ 3,262
Aggregate Intrinsic Value, Exercisable	3,262
Aggregate Intrinsic Value, Vested and expected to vest	$ 3,262