Income Taxes - Reconciliation of Effective Tax Rate (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Tax Disclosure [Abstract]
Federal statutory tax rate	35.00%	35.00%	35.00%	35.00%
State income taxes, net of federal benefit	2.20%	3.30%	2.20%	2.90%
Change in valuation allowance	0.00%	(0.30%)	0.00%	(0.20%)
Domestic production activities deduction	(2.70%)	(2.40%)	(2.70%)	(2.40%)
Other	0.60%	0.30%	0.40%	0.30%
Effective income tax rate	35.10%	35.90%	34.90%	35.60%