Fair Value Measurements (Reconciliation Of Assets Measured At Fair Value On A Recurring Basis) (Details) - Significant Unobservable Inputs (Level 3) [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 3,375	$ 1,841	$ 3,042	$ 1,678
Total increase (decrease) in unrealized gains included in cost of products sold	358	544	1,679	1,358
Purchases	7,351	3,181	20,899	9,600
Sales	(7,346)	(2,703)	(21,334)	(9,838)
Settlements	(311)	(96)	(1,134)	(331)
Transfers into Level 3	239	303	1,210	347
Transfers out of Level 3	(679)	(398)	(1,375)	(142)
Balance at end of period	2,987	2,672	2,987	2,672
Inventories Carried At Market [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	2,824	1,399	2,183	1,477
Total increase (decrease) in unrealized gains included in cost of products sold	70	258	875	626
Purchases	7,351	3,181	20,899	9,600
Sales	(7,346)	(2,703)	(21,334)	(9,838)
Settlements	0	0	0	0
Transfers into Level 3	205	290	1,131	290
Transfers out of Level 3	(602)	(333)	(1,252)	(63)
Balance at end of period	2,502	2,092	2,502	2,092
Commodity Derivative Contracts Gains [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	551	442	859	201
Total increase (decrease) in unrealized gains included in cost of products sold	288	286	804	732
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(311)	(96)	(1,134)	(331)
Transfers into Level 3	34	13	79	57
Transfers out of Level 3	(77)	(65)	(123)	(79)
Balance at end of period	$ 485	$ 580	$ 485	$ 580