Fair Value Measurements (Reconciliation Of Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 129	$ 252
Total increase (decrease) in unrealized gains included in cost of products sold	579	305
Purchases	16	17
Sales	(15)	(31)
Settlements	(476)	(566)
Transfers into Level 3	158	177
Transfers out of Level 3	(219)	(25)
Balance at end of period	172	129
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 gains included in cost of products sold	566	315
Purchases	0	0
Sales	0	0
Settlements	(476)	(566)
Transfers into Level 3	158	177
Transfers out of Level 3	(219)	(25)
Balance at end of period	142	113
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 gains included in cost of products sold	13	(10)
Purchases	16	17
Sales	(15)	(31)
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at end of period	$ 30	$ 16