Investments, Loans and Long-Term Receivables (Summary of Equity Method Investments) (Details) - Chevron Phillips Chemical Company LLC - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Summary of financial information
Revenues and other income	$ 2,748	$ 2,539
Income before income taxes	600	521
Net income	$ 585	$ 503