Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash, Cash Equivalents and Restricted Cash:
Cash and cash equivalents		$ 1,059.9	$ 334.7
Restricted cash		98.2	75.3
Total cash, cash equivalents and restricted cash shown in the Statements of Consolidated Cash Flows		1,158.1	410.0	$ 410.1	$ 70.3
Allowance for Doubtful Accounts [Member]
Movement in valuation allowances and reserves [Roll Forward]
Balance at beginning of period		12.4	11.5	12.1
Charged to costs and expenses		8.4	1.2	0.7
Charged to other accounts	[1]	28.7	0.0	0.0
Deductions		(3.0)	(0.3)	(1.3)
Balance at end of period		$ 46.5	$ 12.4	$ 11.5
Minor Investment [Member] | Minimum [Member]
Consolidation Policy [Abstract]
Equity method of ownership interest		3.00%
Minor Investment [Member] | Maximum [Member]
Consolidation Policy [Abstract]
Equity method of ownership interest		50.00%
Major Investment [Member] | Minimum [Member]
Consolidation Policy [Abstract]
Equity method of ownership interest		20.00%
Major Investment [Member] | Maximum [Member]
Consolidation Policy [Abstract]
Equity method of ownership interest		50.00%

[1] Amount presented for 2020 primarily relates to the reclassification of deferred revenue balances to allowance for doubtful accounts in connection with customer bankruptcies and contractual disputes.