Retirement Plans (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014 Person	Sep. 30, 2013	Sep. 30, 2012
Retirement Plans [Line Items]
Defined benefit plan, pension plans with accumulated benefit obligations in excess of plan assets, aggregate projected benefit obligation	$ 3,413	$ 3,069
Defined benefit plan, pension plans with accumulated benefit obligations in excess of plan assets, aggregate accumulated benefit obligation	3,363	2,981
Defined benefit plan, pension plans with accumulated benefit obligations in excess of plan assets, aggregate fair value of plan assets	2,642	2,392
Total employer and employee contributions to defined benefit plans	164
Voluntary contributions made by the company to defined benefit plans	84
Estimated future employer contributions to defined benefit plans in next fiscal year	64
Modification in salaried plans to limit company's cost of future annual retiree medical benefits	150.00%
Projected prescription drug subsidy receipts per year over the next ten years	2
Matching contributions charged to expense for defined contribution savings plans	132	118	105
Number of multiemployer benefit plans in which the Company participates	300
Employer contributions to multiemployer pension plans	44	44	47
Postretirement Benefits
Retirement Plans [Line Items]
Defined Benefit Plan, Benefit Obligation	224	245	266
Total employer and employee contributions to defined benefit plans	8
Voluntary contributions made by the company to defined benefit plans	6
Global Workplace Solutions
Retirement Plans [Line Items]
Defined Benefit Plan, Benefit Obligation	$ 626