Retirement Plans Components of Net Periodic Benefit Cost (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Components of Net Periodic Benefit Cost:
Net actuarial (gain) loss	$ (405)	$ 447	$ 384
U.S. Pension Plans
Components of Net Periodic Benefit Cost:
Service cost	90	69	66
Interest cost	151	150	145
Expected return on plan assets	(232)	(214)	(203)
Net actuarial (gain) loss	(433)	432	336
Amortization of prior service cost (credit)	1	1	1
Curtailment gain	0	0	0
Settlement (gain) loss	(69)	0	0
Net periodic benefit cost (credit)	(492)	438	345
Expense Assumptions:
Discount rate	4.15%	5.25%	5.50%
Expected return on plan assets	8.00%	8.50%	8.50%
Rate of compensation increase	3.25%	3.30%	3.20%
Non-U.S. Pension
Components of Net Periodic Benefit Cost:
Service cost	38	41	34
Interest cost	64	73	70
Expected return on plan assets	(71)	(75)	(75)
Net actuarial (gain) loss	48	30	43
Amortization of prior service cost (credit)	(1)	(1)	2
Curtailment gain	(26)	(2)	(19)
Settlement (gain) loss	(1)	0	4
Net periodic benefit cost (credit)	51	66	59
Expense Assumptions:
Discount rate	3.40%	4.00%	4.00%
Expected return on plan assets	4.55%	5.15%	5.50%
Rate of compensation increase	2.45%	2.45%	3.00%
Postretirement Benefits
Components of Net Periodic Benefit Cost:
Service cost	5	5	5
Interest cost	11	13	13
Expected return on plan assets	(13)	(11)	0
Net actuarial (gain) loss	(20)	(15)	5
Amortization of prior service cost (credit)	(17)	(17)	(17)
Curtailment gain	0	0	0
Settlement (gain) loss	0	0	0
Net periodic benefit cost (credit)	$ (34)	$ (25)	$ 6
Expense Assumptions:
Discount rate	4.15%	5.25%	5.50%
Expected return on plan assets	5.80%	6.30%
Rate of compensation increase