Earnings Per Share - Calculation of Basic and Diluted Weighted Average Shares Outstanding and Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Basic:
Net income (loss)	$ (327,388)	$ 25,943
Net income attributable to participating securities		(537)
Net income (loss) attributable to common stock-basic	(327,388)	25,406
Diluted:
Net income (loss)	(327,388)	25,943
Net income attributable to participating securities		(537)
Net income (loss) attributable to common stock-diluted	$ (327,388)	$ 25,406
Weighted average shares (denominator):
Weighted average shares-basic	55,181	49,013
Dilutive effect of stock options		49
Weighted average shares-diluted	55,181	49,062
Basic earnings (loss) per share	$ (5.93)	$ 0.52
Diluted earnings (loss) per share	$ (5.93)	$ 0.52