Summary of Income Tax Expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current Income Tax Expense:
Federal	$ 91,664	$ 116,234	$ 0
State	9,393	10,819	9,797
Current Income Tax Expense (Benefit), Total	101,057	127,053	9,797
Deferred Income Tax Expense (Benefit):
Federal	(35,941)	(23,035)	62,015
State	(822)	(206)	(2,202)
Deferred Income Tax Expense (Benefit), Total	(36,763)	(23,241)	59,813
INCOME TAXES	$ 64,294	$ 103,812	$ 69,610