v3.3.1.900

Summary of Significant Accounting Policies - Reconciliations of Numerators and Denominators of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net (loss) income - basic	$ (5,759)	$ (148,787)	$ (11,850)	$ (7,708)	$ 26,987	$ 22,447	$ 3,793	$ 2,945	$ 64,321	$ 495	$ 7,787	$ (347)	$ (174,104)	$ 56,172	$ 72,256
Weighted average shares - basic													40,464,283	39,407,733	38,997,815
Dilution effect of share-based compensation, treasury method														12,132	21,334
Weighted average shares - diluted													40,464,283	39,419,865	39,019,149
Basic	$ (0.14)	$ (3.67)	$ (0.29)	$ (0.19)	$ 0.68	$ 0.57	$ 0.10	$ 0.08	$ 1.65	$ 0.01	$ 0.20	$ (0.01)	$ (4.30)	$ 1.43	$ 1.85
Diluted	$ (0.14)	$ (3.67)	$ (0.29)	$ (0.19)	$ 0.68	$ 0.57	$ 0.10	$ 0.08	$ 1.65	$ 0.01	$ 0.20	$ (0.01)	$ (4.30)	$ 1.42	$ 1.85

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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