Significant Accounting Policies (Details) (USD $) In Billions, unless otherwise specified	12 Months Ended
	Sep. 30, 2013 item	Sep. 30, 2012	Sep. 30, 2011
Fiscal Year
Fiscal year period	364 days	364 days	364 days
Revenue Recognition
Other direct costs	$ 3.2	$ 3.0	$ 2.9
Cost-Plus Contracts
Number of major types of cost-plus contracts the Company enters into	2
Fixed Price Contracts
Number of types of fixed price contracts	2
Pension Plans
Amortization period of the difference between actual return and expected return	5 years
Specified percentage to be exceeded for amortization of cumulative, net unrecognized gains or losses (as a percent)	10.00%