Related Party Transactions (Management and Other Transactions) (Narrative) (Details) - Management [Member] - Equipment, Supplies And Services [Member] - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Related Party Transaction [Line Items]
Payments, related party	$ 80.9	$ 108.0	$ 134.4
Payables, related party	8.9	14.7
Revenue, related party	4.1	$ 2.3	$ 10.3
Receivables, related party	$ 0.5

Amount for accounts payable to related parties.

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