Fair Value Measurements (Reconciliation Of Assets Measured At Fair Value On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 2,091	$ 1,888
Total increase (decrease) in unrealized gains included in cost of products sold	559	(171)
Purchases	16,114	14,638
Sales	(16,384)	(14,107)
Settlements	(948)	(567)
Transfers into Level 3	439	554
Transfers out of Level 3	(177)	(144)
Balance at end of period	1,694	2,091
Inventories Carried At Market [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	1,812	1,745
Total increase (decrease) in unrealized gains included in cost of products sold	15	(645)
Purchases	16,114	14,638
Sales	(16,384)	(14,107)
Transfers into Level 3	44	231
Transfers out of Level 3	(110)	(50)
Balance at end of period	1,491	1,812
Commodity Derivative Contracts Gains [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	279	143
Total increase (decrease) in unrealized gains included in cost of products sold	544	474
Settlements	(948)	(567)
Transfers into Level 3	395	323
Transfers out of Level 3	(67)	(94)
Balance at end of period	$ 203	$ 279