Accumulated Other Comprehensive Income (Parenthetical) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Pension and post retirement [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amortization of deferred actuarial losses, tax	$ (13)	$ (21)	$ (26)	$ (42)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Deferred cash flow hedging gains (losses), tax	6	(1)	6	0
Reclass of deferred cash flow hedging (losses), tax	$ 0	$ 3	$ (1)	$ 3