Supplemental Cash Flow Information (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Supplemental Cash Flow Elements [Abstract]
Payments of interest and commitment fees	$ 35.4	$ 33.7
Interest paid, capitalized	0.7	0.5
Incurred liabilities for fixed and intangible asset additions	$ 27.1	$ 17.2