Derivative Instruments and Hedging Activity - Fair Value of Derivative Instruments Included in Balance Sheets (Details) - Cash Flow Hedges [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Assets	$ 0	$ 0
Liabilities	1,020	418
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Assets	0	0
Other Noncurrent Assets [Member]
Derivatives, Fair Value [Line Items]
Assets	0	0
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Liabilities	19	1
Derivatives [Member]
Derivatives, Fair Value [Line Items]
Liabilities	1,001	417
Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Assets	0	0
Liabilities	1,020	418
Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivatives, Fair Value [Line Items]
Assets	53	9
Liabilities	$ 1,073	$ 427