Income Taxes (Schedule of Effective Tax Rate Reconciliation) (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax provision calculated using the federal statutory income tax rate	$ 224,833	$ 299,900	$ 323,416
State income taxes, net of federal income tax benefit	13,518	30,955	29,555
Effect of statutory rate change	(4,178)	(429)	(578)
Other	(1,390)	1,071	(1,681)
Total income tax expense	$ 232,783	$ 331,497	$ 350,712