Summarized Financial Data - Chevron U.S.A. Inc. (Details 1) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Subsidiary Statements Captions [Line Items]
Current assets	$ 35,583	$ 28,560
Current liabilities	29,183	27,737
Total CUSA net equity	154,673	149,319	$ 147,911	$ 146,722
Chevron U.S.A. Inc.
Subsidiary Statements Captions [Line Items]
Current assets	15,036	12,163
Other assets	55,209	54,994
Current liabilities	18,329	17,379
Other liabilities	13,049	12,541
Total CUSA net equity	38,867	37,237
Memo: Total debt	$ 3,049	$ 3,056