Basis Of Presentation Derivative Instruments (Details) - Interest Rate Swap - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Derivative [Line Items]
Derivative, Notional Amount	$ 1,600
Not Designated as Hedging Instrument | Interest expense
Derivative [Line Items]
Loss Recognized on Derivatives	51	$ 14
Not Designated as Hedging Instrument | Other current and non-current liabilities
Derivative [Line Items]
Interest rate swap contract - other current and non-current liabilities	96		$ 47
August 2015
Derivative [Line Items]
Derivative, Notional Amount	600
November 2017
Derivative [Line Items]
Derivative, Notional Amount	450
August 2020
Derivative [Line Items]
Derivative, Notional Amount	400
November 2022
Derivative [Line Items]
Derivative, Notional Amount	$ 150