Fair Value Measurements - Fair Values - Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Fair Value
Financial assets
Current assets	$ 4	$ 4
Other noncurrent assets	35	26
Total financial assets	39	30
Financial liabilities
Other current liabilities	62	62
Long-term debt, including current portion	6,044	6,174
Deferred credits and other liabilities	105	99
Total financial liabilities	6,211	6,335
Carrying Amount
Financial assets
Current assets	4	4
Other noncurrent assets	49	38
Total financial assets	53	42
Financial liabilities
Other current liabilities	99	90
Long-term debt, including current portion	5,931	5,529
Deferred credits and other liabilities	84	86
Total financial liabilities	$ 6,114	$ 5,705