Summarized Financial Data - Chevron U.S.A. Inc. (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues and Other Income	[1]		$ 33,892		$ 98,293
Costs and other deductions		$ 38,288	33,547	$ 108,310	96,366
Net income attributable to CUSA		$ 4,047	1,952	11,094	6,084
Includes excise, value-added and similar taxes			1,867		5,315
Oil and Gas
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues and Other Income			$ 33,892		98,293
Chevron U.S.A. Inc.
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Costs and other deductions				90,912	75,403
Net income attributable to CUSA				2,929	1,315
Includes excise, value-added and similar taxes					3,268
Chevron U.S.A. Inc. | Oil and Gas
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Total Revenues and Other Income				$ 93,434	$ 75,759

[1] The three-month and nine-month comparative periods ended September 30, 2017, include excise, value-added and similar taxes of $1,867 million and $5,315 million, respectively, collected on behalf of third parties. Beginning in 2018, these taxes are netted in "Taxes other than on income" in accordance with ASU 2014-09. Refer to Note 17, "Revenue" beginning on page 24.