Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income from Continuing Operations Before Income Tax Expense from Domestic and Foreign Operations
U.S. operations	$ 4,677,000,000	$ 3,531,000,000	$ 4,015,000,000
International operations	875,000,000	445,000,000	725,000,000
Income from continuing operations before income tax expense	5,552,000,000	3,976,000,000	4,740,000,000
Reconciliation of Income Tax Expense Related to Income from Continuing Operations Before Income Tax Expense
Federal income tax expense at the U.S. federal statutory rate	1,943,000,000	1,392,000,000	1,659,000,000
U.S. state income tax expense, net of U.S. federal income tax effect	62,000,000	62,000,000	64,000,000
U.S. manufacturing deduction	(74,000,000)	(36,000,000)	(33,000,000)
International operations	(88,000,000)	(69,000,000)	(96,000,000)
Permanent differences	(16,000,000)	(104,000,000)	20,000,000
Change in tax law	0	(32,000,000)	0
Other, net	(50,000,000)	41,000,000	12,000,000
Income tax expense	1,777,000,000	1,254,000,000	1,626,000,000
Current:
U.S. federal	1,196,000,000	635,000,000	515,000,000
U.S. state	59,000,000	36,000,000	22,000,000
International	77,000,000	82,000,000	126,000,000
Total current	1,332,000,000	753,000,000	663,000,000
Deferred:
U.S. federal	268,000,000	459,000,000	854,000,000
U.S. state	36,000,000	59,000,000	77,000,000
International	141,000,000	(17,000,000)	32,000,000
Total deferred	445,000,000	501,000,000	963,000,000
Income tax expense	1,777,000,000	1,254,000,000	1,626,000,000
Deferred income tax assets:
Tax credit carryforwards	37,000,000	48,000,000
Net operating losses (NOLs)	436,000,000	338,000,000
Inventories	160,000,000	264,000,000
Property, plant, and equipment	0	8,000,000
Compensation and employee benefit liabilities	358,000,000	178,000,000
Environmental liabilities	92,000,000	92,000,000
Other	178,000,000	187,000,000
Total deferred income tax assets	1,261,000,000	1,115,000,000
Less: Valuation allowance	(393,000,000)	(347,000,000)
Net deferred income tax assets	868,000,000	768,000,000
Deferred income tax liabilities:
Property, plant, and equipment	6,682,000,000	6,536,000,000
Deferred turnaround costs	356,000,000	331,000,000
Inventories	426,000,000	310,000,000
Investments	152,000,000	94,000,000
Other	73,000,000	81,000,000
Total deferred income tax liabilities	7,689,000,000	7,352,000,000
Net deferred income tax liabilities	6,821,000,000	6,584,000,000
Valuation Allowance Allocation
Deferred tax assets valuation allowance	393,000,000	347,000,000
Reconciliation of the Change in Unrecognized Tax Benefits RollForward
Balance as of beginning of year	950,000,000	341,000,000	326,000,000
Additions based on tax positions related to the current year	35,000,000	64,000,000	11,000,000
Additions for tax positions related to prior years	118,000,000	576,000,000	40,000,000
Reductions for tax positions related to prior years	(67,000,000)	(26,000,000)	(36,000,000)
Reductions for tax positions related to the lapse of applicable statute of limitations	(1,000,000)	(4,000,000)	0
Settlements	(46,000,000)	(1,000,000)	0
Balance as of end of year	989,000,000	950,000,000	341,000,000
Reconciliation of Unrecognized Tax Benefits to Uncertain Tax Position Liabilities
Unrecognized tax benefits	989,000,000	950,000,000	341,000,000
Tax refund claim not recognized in our financial statements	(118,000,000)	(576,000,000)	(40,000,000)
Penalties, interest (net of U.S. federal and state income tax effect), and the U.S. federal income tax effect of state unrecognized tax benefits	49,000,000	49,000,000
Uncertain tax position liabilities	484,000,000	443,000,000
Income Taxes (Textual)
Statutory federal income tax rate	35.00%	35.00%	35.00%
Gain on disposition of retained interest in CST Brands, Inc.	0	325,000,000	0
Income tax benefit related to discontinued operations	0	0	0
Increase in valuation allowance	46,000,000
Cumulative undistributed earnings of foreign subsidiaries	2,900,000,000
Additions for tax positions related to prior years	118,000,000	576,000,000	40,000,000
Income tax benefits if recognized that would impact the effective tax rate	768,000,000	763,000,000
Possible reduction to unrecognized tax benefit	133,000,000
Interest expense and penalties recognized		12,000,000	23,000,000
Interest expense and penalties accrued	141,000,000	145,000,000
Tax Years 2005 to 2012 [Member]
Reconciliation of the Change in Unrecognized Tax Benefits RollForward
Additions for tax positions related to prior years	554,000,000	556,000,000
Reconciliation of Unrecognized Tax Benefits to Uncertain Tax Position Liabilities
Tax refund claim not recognized in our financial statements	(554,000,000)	(556,000,000)
Income Taxes (Textual)
Additions for tax positions related to prior years	554,000,000	556,000,000
Consolidated Statement Of Income [Member]
Deferred income tax assets:
Less: Valuation allowance	(386,000,000)
Valuation Allowance Allocation
Deferred tax assets valuation allowance	386,000,000
Additional Paid-in Capital [Member]
Deferred income tax assets:
Less: Valuation allowance	(7,000,000)
Valuation Allowance Allocation
Deferred tax assets valuation allowance	7,000,000
State and Local Jurisdiction [Member]
Income Tax Credit and Loss Carryforwards
NOL	6,574,000,000
State and Local Jurisdiction [Member] | Minimum [Member]
Income Tax Credit and Loss Carryforwards
NOL, expiration	Dec. 31, 2015
State and Local Jurisdiction [Member] | Maximum [Member]
Income Tax Credit and Loss Carryforwards
NOL, expiration	Dec. 31, 2034
State and Local Jurisdiction [Member] | U S State Income Tax Credits Limited [Member]
Income Tax Credit and Loss Carryforwards
U.S. state income tax credits	53,000,000
State and Local Jurisdiction [Member] | U S State Income Tax Credits Limited [Member] | Minimum [Member]
Income Tax Credit and Loss Carryforwards
Income tax credits, expiration	Dec. 31, 2015
State and Local Jurisdiction [Member] | U S State Income Tax Credits Limited [Member] | Maximum [Member]
Income Tax Credit and Loss Carryforwards
Income tax credits, expiration	Dec. 31, 2027
Foreign Tax Authority [Member]
Income Tax Credit and Loss Carryforwards
NOL	$ 1,630,000,000