Fair Value Measurements (Reconciliation Of Assets Measured At Fair Value On A Recurring Basis) (Details) (Significant Unobservable Inputs (Level 3) [Member], Fair Value, Measurements, Recurring [Member], USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Dec. 31, 2012	Jun. 30, 2012
Inventories Carried At Market [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	$ 1,462	$ 762
Total increase (decrease) in unrealized gains included in cost of products sold	78	88
Purchases	4,866	7,036
Sales	(4,746)	(6,504)
Transfers into Level 3	278	90
Transfers out of Level 3	(193)	(10)
Balance at end of period	1,745	1,462
Commodity Derivative Contracts Gains [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	171	112
Total increase (decrease) in unrealized gains included in cost of products sold	127	592
Purchases		2
Settlements	(231)	(490)
Transfers into Level 3	161	108
Transfers out of Level 3	(85)	(153)
Balance at end of period	143	171
Total Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance at beginning of period	1,633	874
Total increase (decrease) in unrealized gains included in cost of products sold	205	680
Purchases	4,866	7,038
Sales	(4,746)	(6,504)
Settlements	(231)	(490)
Transfers into Level 3	439	198
Transfers out of Level 3	(278)	(163)
Balance at end of period	$ 1,888	$ 1,633