Summarized Financial Data - Chevron U.S.A. Inc. - Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Subsidiary Statements Captions [Line Items]
Current assets	$ 24,803		$ 28,329
Current liabilities	19,664		26,530
Total CUSA net equity	132,038	$ 134,386	145,208	$ 156,892	$ 157,451	$ 155,642
Chevron U.S.A. Inc.
Subsidiary Statements Captions [Line Items]
Current assets	9,523		13,059
Other assets	49,582		50,796
Current liabilities	12,062		18,291
Other liabilities	14,415		12,565
Total CUSA net equity	32,628		32,999
Memo: Total debt	$ 7,132		$ 3,222