Earnings Per Share - Calculation of Basic and Diluted Weighted Average Shares Outstanding and Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic:
Net income (loss)	$ (291,965)	$ (29,415)	$ (772,259)	$ 972
Net income attributable to participating securities	0	0	0	(22)
Net income (loss) attributable to common stock - basic	(291,965)	(29,415)	(772,259)	950
Diluted:
Net income (loss)	(291,965)	(29,415)	(772,259)	972
Net income attributable to participating securities	0	0	0	(22)
Net income (loss) attributable to common stock - diluted	$ (291,965)	$ (29,415)	$ (772,259)	$ 950
Weighted average shares (denominator):
Weighted average shares - basic (in shares)	55,282	54,866	55,238	51,998
Dilutive effect of stock options (in shares)	0	0	0	53
Dilutive effect of convertible notes (in shares)	0	0	0	88
Weighted average shares - diluted (in shares)	55,282	54,866	55,238	52,139
Basic earnings (loss) per share (usd per share)	$ (5.28)	$ (0.54)	$ (13.98)	$ 0.02
Diluted earnings (loss) per share (usd per share)	$ (5.28)	$ (0.54)	$ (13.98)	$ 0.02