Income Taxes - Income Tax (Benefit) Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Components Of Income Tax Expense Benefit Continuing Operations [Abstract]
Income tax (benefit) expense	$ (61,975)	$ 117,976	$ (39,609)	$ 136,933
Effective tax rate	34.30%	40.80%	30.30%	40.20%