Pension & Postretirement Expenses (Summary Of Net Periodic Pension And Net Postretirement Plan Expenses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Pension And Postretirement Plan Expenses [Line Items]
Service cost	$ 27	$ 23	$ 54	$ 47
Interest cost	61	60	121	122
Expected return on plan assets	(92)	(86)	(184)	(172)
Net amortization	42	37	85	73
Total	$ 38	$ 34	$ 76	$ 70