Fair Value Measurements (Reconciliation Of Assets Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2015		Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 180		$ 149		$ 205		$ 371
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	1,217		2,123		1,694		2,091
Total increase (decrease) in realized/unrealized gains included in cost of products sold	57	[1]	92	[2]	(166)	[3]	15	[4]
Purchases	2,851		3,845		5,668		7,948
Sales	(2,890)		(4,465)		(5,693)		(8,359)
Settlements	(117)		(183)		(261)		(363)
Transfers into Level 3	132		115		186		177
Transfers out of Level 3	(70)		(149)		(248)		(131)
Balance at end of period	1,180		1,378		1,180		1,378
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	1,039		1,871		1,491		1,812
Total increase (decrease) in realized/unrealized gains included in cost of products sold	17	[1]	(32)	[2]	(275)	[3]	(207)	[4]
Purchases	2,851		3,845		5,668		7,948
Sales	(2,890)		(4,465)		(5,693)		(8,359)
Settlements	0		0		0		0
Transfers into Level 3	74		56		73		56
Transfers out of Level 3	(65)		(136)		(238)		(111)
Balance at end of period	1,026		1,139		1,026		1,139
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	178		252		203		279
Total increase (decrease) in realized/unrealized gains included in cost of products sold	40	[1]	124	[2]	109	[3]	222	[4]
Purchases	0		0		0		0
Sales	0		0		0		0
Settlements	(117)		(183)		(261)		(363)
Transfers into Level 3	58		59		113		121
Transfers out of Level 3	(5)		(13)		(10)		(20)
Balance at end of period	$ 154		$ 239		$ 154		$ 239

[1] Includes increase in unrealized gains of $180 million relating to Level 3 assets still held at June 30, 2015.

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

[3] * Includes increase in unrealized gains of $205 million relating to Level 3 assets still held at June 30, 2015.

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