Lease Obligations (Finance Leases) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Leases [Abstract]
Finance leases, assets, gross	$ 387.2	$ 387.2	$ 337.6
Finance leases, assets, net	314.3	314.3	$ 246.8
Finance leases, assets, depreciation	$ 11.2	$ 21.2