Fair Value Measurements - Fair Values - Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value
Financial assets
Current assets	$ 3	$ 4
Other noncurrent assets	22	26
Total financial assets	25	30
Financial liabilities
Other current liabilities	42	62
Long-term debt, including current portion	3,992	6,174
Deferred credits and other liabilities	90	99
Total financial liabilities	4,124	6,335
Carrying Amount
Financial assets
Current assets	4	4
Other noncurrent assets	40	38
Total financial assets	44	42
Financial liabilities
Other current liabilities	95	90
Long-term debt, including current portion	5,529	5,529
Deferred credits and other liabilities	81	86
Total financial liabilities	$ 5,705	$ 5,705