Risk Management Activities and Fair Value Measurements - Derivative Notional Amounts and Fair Value (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Jun. 30, 2011
Cash Flow Hedging [Member]
Derivative [Line Items]
Notional amount	$ 840	$ 847
Fair Value Asset (Liability)	(105)	(114)
Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	0	0
Fair Value Asset (Liability)	0	0
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Notional amount	831	831
Fair Value Asset (Liability)	(105)	(118)
Cash Flow Hedging [Member] | Commodity Contract [Member]
Derivative [Line Items]
Notional amount	9	16
Fair Value Asset (Liability)	0	4
Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Notional amount	10,971	10,308
Fair Value Asset (Liability)	256	163
Net Investment Hedging [Member]
Derivative [Line Items]
Notional amount	1,758	1,540
Fair Value Asset (Liability)	32	(138)
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Notional amount	11,216	14,996
Fair Value Asset (Liability)	49	138
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Notional amount	11,059	14,957
Fair Value Asset (Liability)	47	139
Not Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative [Line Items]
Notional amount	157	39
Fair Value Asset (Liability)	$ 2	$ (1)