Fair Value Measurements (Reconciliation Of Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2016		Jun. 30, 2015		Jun. 30, 2016		Jun. 30, 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)	$ 419		$ 215		$ 498		$ 270
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	134		238		129		252
Total increase (decrease) in unrealized losses included in cost of products sold	406	[1]	209	[2]	498	[3]	268	[4]
Purchases	1		6		2		12
Sales	(1)		(6)		(8)		(28)
Settlements	(73)		(114)		(146)		(249)
Transfers into Level 3	67		54		83		136
Transfers out of Level 3	(22)		(11)		(46)		(15)
Balance at end of period	512		376		512		376
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	23		20		16		40
Total increase (decrease) in unrealized losses included in cost of products sold	(11)	[1]	(6)	[2]	2	[3]	(11)	[4]
Purchases	1		6		2		12
Sales	(1)		(6)		(8)		(28)
Settlements	0		0		0		0
Transfers into Level 3	0		0		0		0
Transfers out of Level 3	0		(1)		0		0
Balance at end of period	12		13		12		13
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	111		218		113		212
Total increase (decrease) in unrealized losses included in cost of products sold	417	[1]	215	[2]	496	[3]	279	[4]
Purchases	0		0		0		0
Sales	0		0		0		0
Settlements	(73)		(114)		(146)		(249)
Transfers into Level 3	67		54		83		136
Transfers out of Level 3	(22)		(10)		(46)		(15)
Balance at end of period	$ 500		$ 363		$ 500		$ 363

[1] Includes increase in unrealized losses of $419 million relating to Level 3 liabilities still held at June 30, 2016.

[2] * Includes increase in unrealized losses of $215 million relating to Level 3 liabilities still held at June 30, 2015.

[3] * Includes increase in unrealized losses of $498 million relating to Level 3 liabilities still held at June 30, 2016.

[4] * Includes increase in unrealized losses of $270 million relating to Level 3 liabilities still held at June 30, 2015