Derivative Financial Instruments (Pre-tax Net Gains (Losses) Relating to Derivatives Designated as Net Investment Hedges) (Details) - Qualifying Hedges - Foreign currency forward contracts - Net Investment Hedges - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Amounts reclassified from AOCI to income	$ 0.0	$ 0.0
Amounts recorded in Other Comprehensive Income	1.1	(13.3)
Total change in AOCI for period	$ 1.1	$ (13.3)