Investments, Loans and Long-Term Receivables (Summary of Financial Information for Equity Method Investments) (Details) - Chevron Phillips Chemical Company LLC - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Summary of financial information
Revenues	$ 2,287	$ 2,186	$ 7,196	$ 6,526
Income before income taxes	345	372	1,469	1,400
Net income	$ 331	$ 355	$ 1,424	$ 1,343