Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - Recurring Basis [Member] - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets:
Cash equivalents	$ 3	$ 16
Interest rate contracts	53	9
Total assets	56	25
Liabilities:
Interest rate contracts	1,073	427
Total liabilities	1,073	427
Level 1 [Member]
Assets:
Cash equivalents	3	16
Interest rate contracts	0	0
Total assets	3	16
Liabilities:
Interest rate contracts	0	0
Total liabilities	0	0
Level 2 [Member]
Assets:
Cash equivalents	0	0
Interest rate contracts	53	9
Total assets	53	9
Liabilities:
Interest rate contracts	1,073	427
Total liabilities	$ 1,073	$ 427