Fair Value Measurements - Fair Values - Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Fair Value
Financial assets
Current assets	$ 4	$ 4
Other noncurrent assets	28	26
Total financial assets	32	30
Financial liabilities
Other current liabilities	61	62
Long-term debt, including current portion	5,558	6,174
Deferred credits and other liabilities	105	99
Total financial liabilities	5,724	6,335
Carrying Amount
Financial assets
Current assets	4	4
Other noncurrent assets	44	38
Total financial assets	48	42
Financial liabilities
Other current liabilities	97	90
Long-term debt, including current portion	5,530	5,529
Deferred credits and other liabilities	84	86
Total financial liabilities	$ 5,711	$ 5,705