Income Taxes - Summary of Income Tax Expense (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 Tax Disclosure [Abstract]
Current expense, Federal									$ 13,203	$ 35,684	$ 52,207
Current expense, State									3,447	2,666	26,610
Total current expense									16,650	38,350	78,817
Deferred expense (benefit), Federal and State									30,329	28,398	(16,111)
Income tax expense	$ 16,061	$ 7,143	$ 10,961	$ 12,814	$ 14,702	$ 22,402	$ 14,366	$ 15,278	$ 46,979	$ 66,748	$ 62,706