Summary of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Earning per share reconciliation
Net income	$ 1,882		$ 8,710		$ 13,151		$ 22,482
Weighted-average common shares outstanding	76,351	[1]	75,910	[1]	76,312	[1]	75,900	[1]
Earnings per share, basic	$ 0.02	[1]	$ 0.11	[1]	$ 0.17	[1]	$ 0.30	[1]
Net income	$ 1,882		$ 8,710		$ 13,151		$ 22,482
Weighted-average common shares outstanding, basic	76,351	[1]	75,910	[1]	76,312	[1]	75,900	[1]
Effect of assumed exercise of stock options, warrants and RSUs	2,302	[1]	2,248	[1]	2,219	[1]	1,844	[1]
Weighted-average common shares outstanding, diluted	78,653	[1]	78,158	[1]	78,531	[1]	77,744	[1]
Earnings per share, diluted	$ 0.02	[1]	$ 0.11	[1]	$ 0.17	[1]	$ 0.29	[1]
Outstanding options and RSUs excluded as impact would be antidilutive	107		66		110		292
Stock Options
Earning per share reconciliation
Weighted-average effect of dilutive securities	1,730	[1]	1,826	[1]	1,754	[1]	1,458	[1]
RSUs
Earning per share reconciliation
Weighted-average effect of dilutive securities	572	[1]	422	[1]	465	[1]	386	[1]

[1] The number of common shares and per share amounts have been retroactively restated for all prior periods presented to reflect the Company's two-for-one common stock split effected in the form of a common stock dividend distributed on April 1, 2014.