Stock-Based Compensation - Summary of Stock Appreciation Rights (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 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 | shares	3,853,367
Number of Shares, Granted | shares	483,000
Number of Shares, Exercised | shares	(150,050)
Number of Shares, Forfeited or expired | shares	(77,133)
Number of Shares, Outstanding, Ending Balance | shares	4,109,184
Number of Shares, Exercisable | shares	3,456,039
Number of Shares, Vested and expected to vest | shares	4,109,184
Weighted-Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 4.53
Weighted-Average Exercise Price, Granted | $ / shares	6.07
Weighted-Average Exercise Price, Exercised | $ / shares	4.03
Weighted-Average Exercise Price, Forfeited or expired | $ / shares	5.39
Weighted-Average Exercise Price, Outstanding, Ending Balance | $ / shares	5.22
Weighted-Average Exercise Price, Exercisable | $ / shares	5.16
Weighted-Average Exercise Price, Vested and expected to vest | $ / shares	$ 5.22
Weighted-Average Remaining Contractual Term, Outstanding	5 years 7 months 28 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 11 months 19 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	5 years 7 months 28 days
Aggregate Intrinsic Value, Outstanding, Ending balance | $	$ 10,610
Aggregate Intrinsic Value, Exercisable | $	10,197
Aggregate Intrinsic Value, Vested and expected to vest | $	$ 10,610
Performance-Based Stock Appreciation Rights [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Outstanding, Beginning Balance | shares	786,034
Number of Shares, Granted | shares	8,000
Number of Shares, Exercised | shares	(15,100)
Number of Shares, Forfeited or expired | shares	(160)
Number of Shares, Outstanding, Ending Balance | shares	778,774
Number of Shares, Exercisable | shares	774,774
Number of Shares, Vested and expected to vest | shares	778,774
Weighted-Average Exercise Price, Outstanding, Beginning Balance | $ / shares	$ 5.51
Weighted-Average Exercise Price, Granted | $ / shares	5.65
Weighted-Average Exercise Price, Exercised | $ / shares	2.92
Weighted-Average Exercise Price, Forfeited or expired | $ / shares	5.65
Weighted-Average Exercise Price, Outstanding, Ending Balance | $ / shares	6.33
Weighted-Average Exercise Price, Exercisable | $ / shares	6.33
Weighted-Average Exercise Price, Vested and expected to vest | $ / shares	$ 6.33
Weighted-Average Remaining Contractual Term, Outstanding	4 years 4 months 17 days
Weighted-Average Remaining Contractual Term, Exercisable	4 years 4 months 6 days
Weighted-Average Remaining Contractual Term, Vested and expected to vest	4 years 4 months 17 days
Aggregate Intrinsic Value, Outstanding, Ending balance | $	$ 2,177
Aggregate Intrinsic Value, Exercisable | $	2,170
Aggregate Intrinsic Value, Vested and expected to vest | $	$ 2,177