Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Tax Disclosure [Abstract]
Current Income Tax Expense (Benefit)	$ (27)	$ (200)	$ (27)	$ (4,815)
Change in deferred income taxes	34,678	(2,555)	60,844	(10,649)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	(98,887)	0	(99,950)	0
Income Tax Expense (Benefit)	$ 64,236	$ 2,755	$ 39,133	$ 15,464
Effective Income Tax Rate Reconciliation, Percent	64.00%		23.00%
EffectiveIncomeTaxRateExcludingValuationAllowance	35.00%	35.00%	36.00%	35.00%