Income Taxes (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Effective income tax
Effective tax rate (as a percent)	13.10%	24.10%	29.60%	33.30%
Annual estimate
Effective income tax
Effective tax rate (as a percent)			38.00%