Receivables (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
U.S. government:
Amount billed	$ 81.3	$ 99.2
Cost and profits not billed	58.2	251.7
Contract receivables	139.5	350.9
Other trade receivables	474.5	633.0
Finance receivables	10.0	5.2
Notes receivable	23.8	24.6
Other receivables	30.2	35.6
Receivables, gross	678.0	1,049.3
Less allowance for doubtful accounts	(18.5)	(18.0)	(21.1)	(29.5)
Receivables, net	659.5	1,031.3
Revenue from undefinitized contract	93.7
Increase in net income due to increase in revenue from undefinitized contract	2.2
Increase in net income per share due to increase in revenue from undefinitized contract (in dollars per share)	$ 0.02
Classification of receivables
Current receivables	646.2	1,018.6
Long-term receivables	13.3	12.7
Receivables, net	659.5	1,031.3
Undefinitization Contracts | Defense
U.S. government:
Revenues	$ 3.5