Risk Management Activities and Fair Value Measurements - Gains (Losses) on Derivative Instruments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				12 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Jun. 30, 2014
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	$ 10				$ 17
Amount of Gain (Loss) Reclassified from AOCI into Income	64	[1]	0	[1]
Cash Flow Hedging [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	2				3
Amount of Gain (Loss) Reclassified from AOCI into Income	2	[1]	2	[1]
Cash Flow Hedging [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	8				14
Amount of Gain (Loss) Reclassified from AOCI into Income	62	[1]	(2)	[1]
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	0	[2]	0	[2]
Fair Value Hedging [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	23	[2]	(29)	[2]
Fair Value Hedging [Member] | Debt [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	(23)	[2]	29	[2]
Net Investment Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in AOCI on Derivatives (Effective Portion)	64				30
Amount of Gain (Loss) Recognized in Income	(1)	[2]	0	[2]
Not Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	$ (413)	[3],[4]	$ 109	[3],[4]

[1] The gain or loss on the effective portion of cash flow hedging relationships is reclassified from AOCI into net income in the same period during which the related item affects earnings. Such amounts are included in the Consolidated Statements of Earnings as follows: interest rate contracts in Interest expense and foreign currency contracts in Selling, general and administrative expense (SG&A) and Interest expense.

[2] The gain or loss on the ineffective portion of interest rate contracts and net investment hedges, if any, is included in the Consolidated Statements of Earnings in Interest expense.

[3] The gain or loss on non-qualifying foreign currency contracts substantially offsets the foreign currency mark-to-market impact of the related exposure.

[4] The gain or loss on foreign currency contracts not designated as hedging instruments is included in the Consolidated Statements of Earnings in SG&A.