Investments (Unconsolidated Equity Investments) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Schedule of Equity Method Investments [Line Items]
Equity income from unconsolidated investments, net	$ (13)	$ (15)	$ (47)	$ (46)
ATC Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Equity income from unconsolidated investments, net	(12)	(11)	(34)	(36)
Other [Member]
Schedule of Equity Method Investments [Line Items]
Equity income from unconsolidated investments, net	$ (1)	$ (4)	$ (13)	$ (10)