Earnings (Loss) Per Share - Schedule of Earnings (loss) Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Earnings Per Share [Abstract]
Basic earnings (loss) per share, Net Income (Loss)	$ 37,336	$ (15,854)	$ (12,095)	$ (56,214)
Diluted earnings (loss) per share, Net Income (Loss)	$ 37,336	$ (15,854)	$ (12,095)	$ (56,214)
Basic earnings (loss) per share, Shares	86,877	88,222	87,642	85,510
Effect of dilutive incentive-based awards, Shares	312
Diluted earnings (loss) per share, Shares	87,189	88,222	87,642	85,510
Basic earnings (loss) per share, Per Share Amount	$ 0.43	$ (0.18)	$ (0.14)	$ (0.66)
Diluted earnings (loss) per share, Per Share Amount	$ 0.43	$ (0.18)	$ (0.14)	$ (0.66)