Leases (Supplemental Cash Flow and Other Information) (Details) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)
Leases [Abstract]
Operating lease cost	$ 16.8	$ 32.7
Operating cash flows used for operating leases		32.9
Right-of-use assets obtained in exchange for operating lease obligations		$ 38.4
Weighted average remaining lease term - operating leases	7 years	7 years
Weighted average discount rate	2.90%	2.90%