Fair Value Measurements - Assets and Liabilities at Fair Value, Recurring (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Derivatives	$ 104	$ 11
Derivatives	8	74
Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Marketable Securities	28	63
Derivatives	104	11
Total Assets at Fair Value	132	74
Derivatives	8	74
Total Liabilities at Fair Value	8	74
Recurring Basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Marketable Securities	28	63
Derivatives	55	1
Total Assets at Fair Value	83	64
Derivatives	5	26
Total Liabilities at Fair Value	5	26
Recurring Basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Marketable Securities	0	0
Derivatives	49	10
Total Assets at Fair Value	49	10
Derivatives	3	48
Total Liabilities at Fair Value	3	48
Recurring Basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Marketable Securities	0	0
Derivatives	0	0
Total Assets at Fair Value	0	0
Derivatives	0	0
Total Liabilities at Fair Value	$ 0	$ 0