Stock-based Compensation - Summary of Stock Appreciation Rights (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Time-Based Stock Appreciation Rights [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance	4,109,184
Number of Shares, Granted	0
Number of Shares, Exercised	(319,790)
Number of Shares, Outstanding, Ending Balance	3,789,394
Number of Shares, Exercisable	3,753,027
Number of Shares, Vested and expected to vest	3,789,394
Weighted-Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 5.22
Weighted-Average Exercise Price, Exercised | $ / shares	5.18
Weighted-Average Exercise Price, Outstanding, Ending Balance | $ / shares	5.23
Weighted-Average Exercise Price, Exercisable | $ / shares	5.23
Weighted-Average Exercise Price, Vested and expected to vest | $ / shares	$ 5.23
Weighted-Average Remaining Contractual Term, Outstanding	4 years 5 months 27 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 4 months 21 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	4 years 5 months 27 days
Aggregate Intrinsic Value, Outstanding, Ending balance | $	$ 13,798
Aggregate Intrinsic Value, Exercisable | $	13,992
Aggregate Intrinsic Value, Vested and expected to vest | $	$ 13,798
Performance-Based Stock Appreciation Rights [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance	778,774
Number of Shares, Granted	0
Number of Shares, Exercised	(19,950)
Number of Shares, Forfeited or expired	(169,400)
Number of Shares, Outstanding, Ending Balance	589,424
Number of Shares, Exercisable	589,424
Number of Shares, Vested and expected to vest	589,424
Weighted-Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 6.33
Weighted-Average Exercise Price, Exercised | $ / shares	2.95
Weighted-Average Exercise Price, Forfeited or expired | $ / shares	10.97
Weighted-Average Exercise Price, Outstanding, Ending Balance | $ / shares	6.06
Weighted-Average Exercise Price, Exercisable | $ / shares	6.06
Weighted-Average Exercise Price, Vested and expected to vest | $ / shares	$ 6.06
Weighted-Average Remaining Contractual Term, Outstanding	4 years 3 months 18 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 4 months 13 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	4 years 3 months 18 days
Aggregate Intrinsic Value, Outstanding, Ending balance | $	$ 2,632
Aggregate Intrinsic Value, Exercisable | $	2,632
Aggregate Intrinsic Value, Vested and expected to vest | $	$ 2,632