Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 167	$ 582
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	551	498
Deferred income tax expense (benefit)	(22)	2
Changes in current assets and current liabilities	130	(1,026)
Changes in deferred charges and credits and other operating activities, net	51	82
Net cash provided by operating activities	877	138
Cash flows from investing activities:
Deferred turnaround and catalyst costs	(219)	(220)
Investments in joint ventures	(63)	(55)
Acquisitions of undivided interests	(1)	(85)
Other investing activities, net	(1)	(8)
Net cash provided by (used in) investing activities	(747)	(752)
Cash flows from financing activities:
Proceeds from debt issuances and borrowings		498
Repayments of debt and finance lease obligations	(907)	(415)
Purchases of common stock for treasury	(36)	(320)
Common stock dividends	(375)	(345)
Acquisition of Valero Energy Partners LP publicly held common units	(950)	0
Contributions from noncontrolling interests	0	32
Distributions to noncontrolling interests	0	(11)
Other financing activities, net	(25)	(12)
Net cash provided by (used in) financing activities	(378)	(573)
Effect of foreign exchange rate changes on cash	43	(5)
Net increase (decrease) in cash and cash equivalents	(205)	(1,192)
Cash and cash equivalents at beginning of period	2,982	5,850
Cash and cash equivalents at end of period	2,777	4,658
Certain variable interest entities (VIEs) [Member]
Cash flows from investing activities:
Capital expenditures	(19)	(28)
Cash flows from financing activities:
Proceeds from debt issuances and borrowings	23	0
Excluding certain variable interest entities (VIEs) [Member]
Cash flows from investing activities:
Capital expenditures	(444)	(356)
Cash flows from financing activities:
Proceeds from debt issuances and borrowings	$ 1,892	$ 498