Derivative Financial Instruments Derivative Financial Instruments (Fair Value Hedges, Financial Position) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Long term debt, current maturities [Domain]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Amount of Hedged Item	$ 1,598	$ 849
Cumulative basis adjustments for fair value hedges	22	7
Long-term Debt [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, Amount of Hedged Item	17,787	17,217
Cumulative basis adjustments for fair value hedges	$ (1)	$ (11)