Financing Agreements (Narrative) (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2012 New Credit Facility [Member]	Dec. 31, 2012 Term Loan [Member]	Dec. 31, 2012 Previous Credit Facility [Member]	Dec. 31, 2012 Potential Increase to Revolving Credit Facility [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2012 Minimum [Member]
Debt Instrument [Line Items]
Deferred gains from the termination of previous interest rate swap agreements	$ 0.9
Senior revolving credit facility, maximum borrowing amount			500.0		500.0	250.0
Aggregate value of debt				200.0
Credit facility expiration date			Aug. 24, 2017
Percent of principal to be repaid over term			37.50%
Number of years under revolving credit facility			5 years
Maximum interest rate during period			2.00%
Ratio of consolidated indebtedness to consolidated EBITDA							3.5
Interest coverage ratio								3.5
Outstanding borrowings			105.0
Undrawn letters of credit			5.8
Current borrowing capacity under the facility			389.2
Fair value of unsecured debentures	55.7	56.2
Fair value of term loan	$ 195.0	$ 197.5