Income Taxes (Components of Income Tax) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current expense
Federal and other	$ 2.7	$ 41.1	$ 0.7
Foreign	25.8	30.5	22.9
Total current income tax expense	28.5	71.6	23.6
Deferred expense (benefit)
Federal and other	11.1	(47.4)	3.5
Foreign	11.6	2.2	2.5
Total deferred income tax expense (benefit)	22.7	(45.2)	6.0
Income tax expense	$ 51.2	$ 26.4	$ 29.6