Fair Value Measurements (Reconciliation Of Assets Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 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)	$ 222		$ 130
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	2,091		1,888
Total increase (decrease) in unrealized gains included in cost of products sold	(68)	[1]	(561)	[2]
Purchases	4,103		4,684
Sales	(3,894)		(3,700)
Settlements	(180)		(96)
Transfers into Level 3	189		88
Transfers out of Level 3	(118)		(58)
Balance at end of period	2,123		2,245
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	1,812		1,745
Total increase (decrease) in unrealized gains included in cost of products sold	(166)	[1]	(697)	[2]
Purchases	4,103		4,684
Sales	(3,894)		(3,700)
Settlements	0		0
Transfers into Level 3	127		40
Transfers out of Level 3	(111)		(50)
Balance at end of period	1,871		2,022
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	279		143
Total increase (decrease) in unrealized gains included in cost of products sold	98	[1]	136	[2]
Purchases	0		0
Sales	0		0
Settlements	(180)		(96)
Transfers into Level 3	62		48
Transfers out of Level 3	(7)		(8)
Balance at end of period	$ 252		$ 223

[1] Includes increase in unrealized gains of $222 million relating to Level 3 assets still held at March 31, 2014.

[2] * Includes increase in unrealized gains of $130 million relating to Level 3 assets still held at March 31, 2013.