Fair Value Measurements (Reconciliation Of Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 263	$ 142
Total increase (decrease) in unrealized gains included in cost of products sold	397	537
Purchases	48	57
Sales	(38)	(89)
Settlements	(451)	(476)
Transfers into Level 3	51	150
Transfers out of Level 3	(44)	(58)
Balance at end of period	$ 226	263
Document Period End Date	Dec. 31, 2019
Commodity Derivative Contracts Losses [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 245	103
Total increase (decrease) in unrealized gains included in cost of products sold	398	526
Purchases	0	0
Sales	0	0
Settlements	(451)	(476)
Transfers into Level 3	51	150
Transfers out of Level 3	(44)	(58)
Balance at end of period	199	245
Inventory Related Payables [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	18	39
Total increase (decrease) in unrealized gains included in cost of products sold	(1)	11
Purchases	48	57
Sales	(38)	(89)
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at end of period	$ 27	$ 18