Fair Value Measurements (Reconciliation Of Assets Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 145		$ 289		$ 516		$ 553
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	1,378		2,193		2,091		1,888
Total increase (decrease) in unrealized gains included in cost of products sold	252	[1]	305	[2]	299	[3]	(305)	[4]
Purchases	2,526		2,896		10,474		11,795
Sales	(2,352)		(3,264)		(10,711)		(11,576)
Settlements	(166)		(153)		(529)		(381)
Transfers into Level 3	473		104		594		244
Transfers out of Level 3	(37)		(547)		(144)		(131)
Balance at end of period	2,074		1,534		2,074		1,534
Significant Unobservable Inputs (Level 3) [Member] | Inventories Carried At Market [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	1,139		1,926		1,812		1,745
Total increase (decrease) in unrealized gains included in cost of products sold	(33)	[1]	162	[2]	(208)	[3]	(677)	[4]
Purchases	2,526		2,896		10,474		11,795
Sales	(2,352)		(3,264)		(10,711)		(11,576)
Settlements	0		0		0		0
Transfers into Level 3	266		35		266		35
Transfers out of Level 3	(24)		(483)		(111)		(50)
Balance at end of period	1,522		1,272		1,522		1,272
Significant Unobservable Inputs (Level 3) [Member] | Commodity Derivative Contracts Gains [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	239		267		279		143
Total increase (decrease) in unrealized gains included in cost of products sold	285	[1]	143	[2]	507	[3]	372	[4]
Purchases	0		0		0		0
Sales	0		0		0		0
Settlements	(166)		(153)		(529)		(381)
Transfers into Level 3	207		69		328		209
Transfers out of Level 3	(13)		(64)		(33)		(81)
Balance at end of period	$ 552		$ 262		$ 552		$ 262

[1] Includes increase in unrealized gains of $145 million relating to Level 3 assets still held at September 30, 2014.

[2] * Includes increase in unrealized gains of $289 million relating to Level 3 assets still held at September 30, 2013.

[3] * Includes increase in unrealized gains of $516 million relating to Level 3 assets still held at September 30, 2014.

[4] * Includes increase in unrealized gains of $553 million relating to Level 3 assets still held at September 30, 2013.