Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Taxes
Effective tax benefit rate (as a percent)	18.70%	38.20%	28.80%	43.60%
U.S. federal statutory rate (as a percent)			35.00%	35.00%
Release of liabilities relating to uncertain tax positions resulting from settlement of 2010 IRS examination	$ 2.3