Income Taxes (Details 2)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Effective tax rate reconciliation
Statutory U.S. federal tax rate	35.00%	35.00%	35.00%
Increase (decrease) in rate resulting from:
Effect of qualified domestic production deduction	(0.80%)	(1.60%)	(1.10%)
Effect of Patient Protection and Affordable Care Act	(0.60%)	0.00%	1.40%
State and local income taxes, net of related federal taxes	3.00%	2.70%	2.50%
Other, net	0.50%	(1.60%)	(0.10%)
Effective tax rate	37.10%	34.50%	37.70%