Long Term Debt (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Aug. 31, 2012 banks
Debt Instrument [Line Items]
Credit facility syndicate, number of participating banks					10
Credit facility, additional borrowing limit		$ 150
Credit facility, borrowings outstanding	370	370	200	0
Credit facility, additional borrowings	230
Voting interest in foreign subsidiaries pledged against credit facility		65.00%
Investment limit in foreign subsidiaries	50	50
Cash investment limit for acquisition of business	75	75
Maximum leverage ratio allowed under debt covenant	2.5	2.5
Minimum fixed charge coverage ratio allowed under debt covenant	3.50	3.50
Leverage ratio, actual	1.40	1.40
Fixed charge coverage ratio, actual	60.53	60.53
Credit facility, origination costs		1.8	1.0	2.6
Credit facility, periodic interest payment		3.7	1.5	0.7
Credit facility, average interest rate during period		1.80%	2.10%	1.60%
Maximum [Member]
Debt Instrument [Line Items]
Credit facility, variable interest rate, length of time between updates		180 days
Minimum [Member]
Debt Instrument [Line Items]
Credit facility, variable interest rate, length of time between updates		30 days
Term Loan [Member]
Debt Instrument [Line Items]
Credit facility, current maximum amount	150	150
Credit facility, revolving loan, repayments of principal due in 2013	7.5	7.5
Credit facility, revolving loan, repayments of principal due in 2014	15.0	15.0
Credit facility, revolving loan, repayments of principal due in 2015	15.0	15.0
Credit facility, revolving loan, repayments of principal due in 2016	22.5	22.5
Credit facility, revolving loan, repayments of principal due in 2017	90.0	90.0
Credit facility, borrowings outstanding	150	150
Credit facility, term loan, interest rate at period end	1.8125%	1.8125%
Revolving Loan [Member]
Debt Instrument [Line Items]
Credit facility, current maximum amount	300	300
Credit facility, borrowings outstanding	$ 220	$ 220
Credit facility, term loan, interest rate at period end	1.8125%	1.8125%
Credit facility, revolving loan, basis spread on federal funds effective rate		0.005%
Credit facility, revolving loan, basis spread on adjusted LIBOR		1.00%
Revolving Loan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Credit facility, revolving loan, interest rate		1.625%
Credit facility, revolving loan, basis spread over base rate		0.625%
Credit facility, revolving loan, commitment fees percentage		0.30%
Revolving Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Credit facility, revolving loan, interest rate		1.25%
Credit facility, revolving loan, basis spread over base rate		0.25%
Credit facility, revolving loan, commitment fees percentage		0.20%