Lease Obligations (Operating Leases) (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating Leased Assets [Line Items]
Operating leases, additions	$ 5.5	$ 5.8
Operating leases, expense	27.4	35.3
Operating leases, variable lease costs	2.2	2.9
Operating leases, short-term leases, expense	$ 110.1	$ 77.5
Minimum [Member]
Operating Leased Assets [Line Items]
Operating leases, term of contract (in years)	1 year
Maximum [Member]
Operating Leased Assets [Line Items]
Operating leases, term of contract (in years)	1 year