Fair Value Measurements (Reconciliation Of Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2015		Sep. 30, 2014		Sep. 30, 2015		Sep. 30, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 12		$ 111		$ 283		$ 397
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	376		181		252		295
Total increase (decrease) in net realized/unrealized losses included in cost of products sold	10	[1]	110	[2]	279	[3]	394	[4]
Purchases	3		12		15		18
Sales	0		(11)		(29)		(42)
Settlements	(219)		(130)		(468)		(580)
Transfers into Level 3	26		127		161		234
Transfers out of Level 3	(8)		(8)		(22)		(38)
Balance at end of period	188		281		188		281
Significant Unobservable Inputs (Level 3) [Member] | Inventory Related Payables [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	13		19		40		34
Total increase (decrease) in net realized/unrealized losses included in cost of products sold	18	[1]	0	[2]	8	[3]	10	[4]
Purchases	3		12		15		18
Sales	0		(11)		(29)		(42)
Settlements	0		0		0		0
Transfers into Level 3	0		0		0		0
Transfers out of Level 3	0		0		0		0
Balance at end of period	34		20		34		20
Significant Unobservable Inputs (Level 3) [Member] | Commodity Derivative Contracts Losses [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	363		162		212		261
Total increase (decrease) in net realized/unrealized losses included in cost of products sold	(8)	[1]	110	[2]	271	[3]	384	[4]
Purchases	0		0		0		0
Sales	0		0		0		0
Settlements	(219)		(130)		(468)		(580)
Transfers into Level 3	26		127		161		234
Transfers out of Level 3	(8)		(8)		(22)		(38)
Balance at end of period	$ 154		$ 261		$ 154		$ 261

[1] Includes increase in unrealized losses of $12 million relating to Level 3 liabilities still held at September 30, 2015.

[2] * Includes increase in unrealized losses of $111 million relating to Level 3 liabilities still held at September 30, 2014.

[3] * Includes increase in unrealized losses of $283 million relating to Level 3 liabilities still held at September 30, 2015.

[4] * Includes increase in unrealized losses of $397 million relating to Level 3 liabilities still held at September 30, 2014.