Fair Value Measurements (Reconciliation Of Assets Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 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)	$ 149		$ 134		$ 371		$ 264
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	2,123		2,245		2,091		1,888
Total increase (decrease) in unrealized gains included in cost of products sold	92	[1]	265	[2]	15	[3]	(287)	[4]
Purchases	3,845		4,215		7,948		8,899
Sales	(4,465)		(4,611)		(8,359)		(8,312)
Settlements	(183)		(132)		(363)		(228)
Transfers into Level 3	115		252		177		300
Transfers out of Level 3	(149)		(41)		(131)		(67)
Balance at end of period	1,378		2,193		1,378		2,193
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	1,871		2,022		1,812		1,745
Total increase (decrease) in unrealized gains included in cost of products sold	(32)	[1]	172	[2]	(207)	[3]	(516)	[4]
Purchases	3,845		4,215		7,948		8,899
Sales	(4,465)		(4,611)		(8,359)		(8,312)
Settlements	0		0		0		0
Transfers into Level 3	56		160		56		160
Transfers out of Level 3	(136)		(32)		(111)		(50)
Balance at end of period	1,139		1,926		1,139		1,926
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	252		223		279		143
Total increase (decrease) in unrealized gains included in cost of products sold	124	[1]	93	[2]	222	[3]	229	[4]
Purchases	0		0		0		0
Sales	0		0		0		0
Settlements	(183)		(132)		(363)		(228)
Transfers into Level 3	59		92		121		140
Transfers out of Level 3	(13)		(9)		(20)		(17)
Balance at end of period	$ 239		$ 267		$ 239		$ 267

[1] Includes increase in unrealized gains of $149 million relating to Level 3 assets still held at June 30, 2014.

[2] * Includes increase in unrealized gains of $134 million relating to Level 3 assets still held at June 30, 2013.

[3] * Includes increase in unrealized gains of $371 million relating to Level 3 assets still held at June 30, 2014.

[4] * Includes increase in unrealized gains of $264 million relating to Level 3 assets still held at June 30, 2013.