Summarized Financial Data - Chevron Phillips Chemical Company LLC (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Summarized Financial Data - Chevron Transport Corporation
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 TCO		$ 4,047	1,952	$ 11,094	6,084
Oil and Gas
Summarized Financial Data - Chevron Transport Corporation
Total Revenues and Other Income			$ 33,892		98,293
Chevron Phillips Chemical Company LLC
Affiliate Statements Captions [Line Items]
Percentage of affiliate by summarized financial information		100.00%		100.00%
Summarized Financial Data - Chevron Transport Corporation
Costs and other deductions				$ 7,475	5,732
Net income attributable to TCO				1,766	1,424
Chevron Phillips Chemical Company LLC | Oil and Gas
Summarized Financial Data - Chevron Transport Corporation
Total Revenues and Other Income				$ 8,773	$ 6,816
Chevron Phillips Chemical Company LLC
Affiliate Statements Captions [Line Items]
Equity method investment, ownership percentage		50.00%		50.00%

[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.