Fair Value Measurements (Reconciliation Of Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016		Mar. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 79		$ 55
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	129		252
Total increase (decrease) in unrealized losses included in cost of products sold	92	[1]	59	[2]
Purchases	1		6
Sales	(7)		(22)
Settlements	(72)		(135)
Transfers into Level 3	15		83
Transfers out of Level 3	(24)		(5)
Balance at end of period	134		238
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	16		40
Total increase (decrease) in unrealized losses included in cost of products sold	13	[1]	(5)	[2]
Purchases	1		6
Sales	(7)		(22)
Settlements	0		0
Transfers into Level 3	0		1
Transfers out of Level 3	0		0
Balance at end of period	23		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	113		212
Total increase (decrease) in unrealized losses included in cost of products sold	79	[1]	64	[2]
Purchases	0		0
Sales	0		0
Settlements	(72)		(135)
Transfers into Level 3	15		82
Transfers out of Level 3	(24)		(5)
Balance at end of period	$ 111		$ 218

[1] Includes increase in unrealized losses of $79 million relating to Level 3 liabilities still held at March 31, 2016.

[2] * Includes increase in unrealized losses of $55 million relating to Level 3 liabilities still held at March 31, 2015.