Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2013

Fair Value Disclosures [Abstract]

Fair value of financial assets and liabilities measured on recurring basis

The tables below present information (in millions) about our assets and liabilities recognized at their fair values in our balance sheets categorized according to the fair value hierarchy of the inputs utilized by us to determine the fair values as of December 31, 2013 and 2012.

We have elected to offset the fair value amounts recognized for multiple similar derivative contracts executed with the same counterparty, including any related cash collateral assets or obligations as shown below; however, fair value amounts by hierarchy level are presented on a gross basis in the tables below. We have no derivative contracts that are subject to master netting arrangements that are reflected gross on the balance sheet.

	December 31, 2013
							Total Gross Fair Value		Effect of Counter-party Netting			Effect of Cash Collateral Netting			Net Carrying Value on Balance Sheet		Cash Collateral Paid or Received Not Offset
	Fair Value Hierarchy
	Level 1		Level 2		Level 3
Assets:
Commodity derivative contracts	$	499	$	38	$	—	$	537	$	(505	)	$	(7	)	$	25	$	—
Investments of certain benefit plans	98		—		11		109		n/a			n/a			109		n/a
Total	$	597	$	38	$	11	$	646	$	(505	)	$	(7	)	$	134
Liabilities:
Commodity derivative contracts	$	492	$	24	$	—	$	516	$	(505	)	$	(6	)	$	5	$	(76	)
Biofuels blending obligation	—		11		—		11		n/a			n/a			11		n/a
Physical purchase contracts	—		5		—		5		n/a			n/a			5		n/a
Foreign currency contracts	8		—		—		8		n/a			n/a			8		n/a
Total	$	500	$	40	$	—	$	540	$	(505	)	$	(6	)	$	29

	December 31, 2012
							Total Gross Fair Value		Effect of Counter-party Netting			Effect of Cash Collateral Netting			Net Carrying Value on Balance Sheet		Cash Collateral Paid or Received Not Offset
	Fair Value Hierarchy
	Level 1		Level 2		Level 3
Assets:
Commodity derivative contracts	$	1,143	$	60	$	—	$	1,203	$	(1,189	)	$	—		$	14	$	—
Physical purchase contracts	—		11		—		11		n/a			n/a			11		n/a
Foreign currency contracts	1		—		—		1		n/a			n/a			1		n/a
Investments of certain benefit plans	87		—		11		98		n/a			n/a			98		n/a
Total	$	1,231	$	71	$	11	$	1,313	$	(1,189	)	$	—		$	124
Liabilities:
Commodity derivative contracts	$	1,138	$	70	$	—	$	1,208	$	(1,189	)	$	(13	)	$	6	$	(114	)
Biofuels blending obligation	—		10		—		10		n/a			n/a			10		n/a
Foreign currency contracts	1		—		—		1		n/a			n/a			1		n/a
Total	$	1,139	$	80	$	—	$	1,219	$	(1,189	)	$	(13	)	$	17

Reconciliation of the beginning and ending balances for fair value measurements developed using significant unobservable inputs

The following is a reconciliation of the beginning and ending balances (in millions) for fair value measurements developed using significant unobservable inputs (Level 3).

	Investments of Certain Benefit Plans						Other Investments
	2013		2012		2011		2013		2012		2011
Balance as of beginning of year	$	11	$	11	$	10	$	—	$	—	$	—
Purchases	—		—		1		—		—		21
Total losses included in refining operating expense	—		—		—		—		—		(21		)
Transfers in and/or out of Level 3	—		—		—		—		—		—
Balance as of end of year	$	11	$	11	$	11	$	—	$	—	$	—
The amount of total losses included in income attributable to the change in unrealized losses relating to assets still held at end of year	$	—	$	—	$	—	$	—	$	—	$	(21	)

Fair value of assets measured on a nonrecurring basis

The table below presents the fair value of certain assets that were measured at fair value on a nonrecurring basis as of December 31, 2012 (in millions) and the related impairment losses recognized. See Note 4 for our impairment analysis for these assets.

							Total Fair Value as of December 31, 2012		Total Losses Recognized During the Year Ended December 31, 2012
	Fair Value Hierarchy
	Level 1		Level 2		Level 3
Assets:
Long-lived assets of the Aruba Refinery	$	—	$	—	$	—	$	—	$	903
Materials and supplies inventories of the Aruba Refinery	—		—		—		—		25
Cancelled capital projects	—		—		2		2		65
Property, plant, and equipment of convenience stores	—		—		8		8		21

Carrying amounts and estimated fair value of financial instruments

Financial instruments that we recognize in our balance sheets at their carrying amounts are shown in the table below (in millions):

	December 31, 2013				December 31, 2012
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial assets:
Cash and temporary cash investments	$	4,292	$	4,292	$	1,723	$	1,723
Financial liabilities:
Debt (excluding capital leases)	6,525		7,659		7,000		8,621