Income Taxes (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Federal income tax expense	$ 59.5	$ 28.9
Foreign income tax expense (benefit)	(16.5)	27.9
Foreign income permanently reinvested	10.4	$ 18.7
Estimated taxes payable on undistributed earnings	$ 51.0