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, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 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)	$ 1	$ 12	$ 499	$ 283
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	512	376	129	252
Total increase (decrease) in unrealized losses included in cost of products sold	2	10	499	279
Purchases	3	3	5	15
Sales	(3)		(11)	(29)
Settlements	(247)	(219)	(392)	(468)
Transfers into Level 3	33	26	115	161
Transfers out of Level 3	(167)	(8)	(212)	(22)
Balance at end of period	133	188	133	188
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	12	13	16	40
Total increase (decrease) in unrealized losses included in cost of products sold	3	18	5	8
Purchases	3	3	5	15
Sales	(3)		(11)	(29)
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	15	34	15	34
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	500	363	113	212
Total increase (decrease) in unrealized losses included in cost of products sold	(1)	(8)	494	271
Purchases	0	0	0	0
Sales	0		0	0
Settlements	(247)	(219)	(392)	(468)
Transfers into Level 3	33	26	115	161
Transfers out of Level 3	(167)	(8)	(212)	(22)
Balance at end of period	$ 118	$ 154	$ 118	$ 154