Consolidated Statements of Cash Flows (Unaudited) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 1,117	$ 398
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	835	770
Asset impairment losses	0	611
Noncash interest expense and other income, net	1	11
Stock-based compensation expense	25	20
Deferred income tax expense	341	480
Changes in current assets and current liabilities	444	565
Changes in deferred charges and credits and other operating activities, net	51	(21)
Net cash provided by operating activities	2,814	2,834
Cash flows from investing activities:
Capital expenditures	(1,211)	(1,420)
Deferred turnaround and catalyst costs	(449)	(264)
Proceeds from the sale of the Paulsboro Refinery	0	160
Minor acquisitions	0	(66)
Other investing activities, net	(23)	9
Net cash used in investing activities	(1,683)	(1,581)
Non-bank debt:
Borrowings	0	300
Repayments	(480)	(862)
Bank credit agreements:
Borrowings	0	1,100
Repayments	0	(1,100)
Accounts receivable sales program:
Proceeds from the sale of receivables	0	1,300
Repayments	0	(1,450)
Purchase of common stock for treasury	(560)	(147)
Proceeds from the exercise of stock options	43	11
Common stock dividends	(220)	(166)
Contributions from noncontrolling interests	45	25
Separation of retail business:
Proceeds from short-term debt	550	0
Cash distributed to Valero by CST Brands, Inc.	500	0
Cash held and retained by CST Brands, Inc. upon separation	(315)	0
Other financing activities, net	24	(2)
Net cash used in financing activities	(413)	(991)
Effect of foreign exchange rate changes on cash	(43)	9
Net increase in cash and temporary cash investments	675	271
Cash and temporary cash investments at beginning of period	1,723	1,024
Cash and temporary cash investments at end of period	$ 2,398	$ 1,295