Pension And Postretirement Plan 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, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Pension And Postretirement Plan Expenses [Line Items]
Service cost	$ 27	$ 20	$ 53	$ 42
Interest cost	57	59	113	119
Expected return on plan assets	(83)	(79)	(166)	(159)
Net amortization	58	43	116	86
Total	$ 59	$ 43	$ 116	$ 88