Fair Value Measurements (Reconciliation Of Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 252	$ 295
Total increase (decrease) in unrealized gains included in cost of products sold	305	556
Purchases	17	29
Sales	(31)	(45)
Settlements	(566)	(785)
Transfers into Level 3	177	256
Transfers out of Level 3	(25)	(54)
Balance at end of period	129	252
Commodity Derivative Contracts Losses [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	212	261
Total increase (decrease) in unrealized gains included in cost of products sold	315	534
Purchases	0	0
Sales	0	0
Settlements	(566)	(785)
Transfers into Level 3	177	256
Transfers out of Level 3	(25)	(54)
Balance at end of period	113	212
Inventory Related Payables [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	40	34
Total increase (decrease) in unrealized gains included in cost of products sold	(10)	22
Purchases	17	29
Sales	(31)	(45)
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at end of period	$ 16	$ 40