Income Taxes - Income Tax Expense (Benefit) Attributable to Income from Continuing Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Taxes [Line Items]
U.S. federal
U.S. state and local									(143)	(1,778)	637
Total	(143)		(25)	25	(1,778)				(143)	(1,778)	637
U.S. federal									58,527	11,873	30,055
U.S. state and local									(24,527)	1,959	4,865
Total	(28,180)	11,866	97,519	(47,205)	31,742	(29,074)	39,007	(27,843)	34,000	13,832	34,920
U.S. federal									58,527	11,873	30,055
U.S. state and local									(24,670)	181	5,502
Total income tax expense	$ (28,323)	$ 11,866	$ 97,494	$ (47,180)	$ 29,964	$ (29,074)	$ 39,007	$ (27,843)	$ 33,857	$ 12,054	$ 35,557