Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Income Taxes
Effective tax rate (as a percent)	28.70%	26.50%
Effective tax rate excluding the net impact of acquisition-related expenses (as a percent)	26.50%
Unrecognized tax benefits, anticipated adjustment for changing facts and circumstances, over the next twelve month period	$ 2.2
Accrued pension benefit obligations and other long-term liabilities
Income Taxes
Liability for unrecognized tax benefits, which if recognized would impact the effective tax rate	$ 129.1