Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current
Federal	$ 80,709,000	$ 60,253,000	$ 80,707,000
State	34,097,000	26,260,000	31,792,000
Total	114,806,000	86,513,000	112,499,000
Deferred
Federal	(10,615,000)	9,525,000	(26,635,000)
State	(9,572,000)	2,784,000	(8,303,000)
Total	(20,187,000)	12,309,000	(34,938,000)
Income tax expense (benefit)
Federal	70,094,000	69,778,000	54,072,000
State	24,525,000	29,044,000	23,489,000
Income tax expense	94,619,000	98,822,000	77,561,000
Effective tax provision (benefit) (as a percent)	28.90%	32.10%	30.60%
Income taxes payable	8,600,000
Income taxes receivable		$ 59,600,000