Pension (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Net Periodic Benefit Cost Abstract
Service cost	$ 8	$ 7	$ 16	$ 14
Interest cost	12	11	24	22
Expected return on plan assets	(9)	(9)	(18)	(18)
Recognized actuarial loss	5	3	9	6
Net periodic benefit costs	$ 16	$ 12	$ 31	$ 24