Fair Value Measurements (Reconciliation Of Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	$ (383)	$ (210)
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	963	226
Total increase (decrease) in unrealized losses included in cost of products sold	401	208
Purchases	12	6
Sales	(2)	(16)
Settlements	(566)	(122)
Transfers into Level 3	65	36
Transfers out of Level 3	(139)	(9)
Balance at end of period	734	329
Significant Unobservable Inputs (Level 3) [Member] | Long-term Debt [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	34
Total increase (decrease) in unrealized losses included in cost of products sold	20
Purchases	0
Balance at end of period	54
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	11	27
Total increase (decrease) in unrealized losses included in cost of products sold	0	3
Purchases	12	6
Sales	(2)	(16)
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance at end of period	21	20
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	918	199
Total increase (decrease) in unrealized losses included in cost of products sold	381	205
Purchases	0	0
Sales	0	0
Settlements	(566)	(122)
Transfers into Level 3	54	36
Transfers out of Level 3	(139)	(9)
Balance at end of period	648	$ 309
Significant Unobservable Inputs (Level 3) [Member] | Foreign Exchange Contracts [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	0
Total increase (decrease) in unrealized losses included in cost of products sold	0
Purchases	0
Sales	0
Settlements	0
Transfers into Level 3	11
Transfers out of Level 3	0
Balance at end of period	$ 11