Derivative Instruments and Hedging Activities (Assets and Liabilities - Current vs. Noncurrent Derivative instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Total asset derivatives	$ 189	$ 171
Total liability derivatives	679	424
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Current	236	126
Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Current	$ 51	$ 72

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