Income Taxes - Income Tax Expense from Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 11,866	$ (29,074)	$ 62,180	$ (17,910)
Effective tax rate	38.20%	35.10%	41.50%	30.90%