Segment Information (Details 2) (Change in estimated total costs, USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Change in estimated total costs
Financial data
Increase in operating profit	$ 12.8	$ 3.7	$ 17.4	$ 10.1
Increase in net income per common share (in dollars per share)	$ 0.31	$ 0.09	$ 0.44	$ 0.25
Increse in net income	$ 8.3	$ 2.3	$ 11.7	$ 6.7