Income Taxes (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Reconciliation between the statutory United States Federal income tax rate and the Company's effective income tax rate
Statutory rate	35.00%	35.00%	35.00%	35.00%
State taxes	1.20%	0.90%	1.20%	0.90%
Domestic production activities deduction	(1.80%)	(2.20%)	(1.90%)	(2.20%)
Noncontrolling interest in partially-owned subsidiaries	(0.90%)	(1.10%)	(0.90%)	(1.20%)
Other, net	0.30%	0.00%	0.30%	0.10%
Effective rate	33.80%	32.60%	33.70%	32.60%