Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Taxes [Abstract]
Income Tax Expense (Benefit)	$ 16.0	$ 46.1
Effective Income Tax Rate Reconciliation, Percent	21.70%	37.20%
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount	$ 12.0