Stock Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended		3 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member]	Dec. 31, 2011 Restricted Stock Units (RSUs) [Member]	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member] Time Based Restricted Stock Unit [Member]	Dec. 31, 2012 Restricted Stock Units (RSUs) [Member] Performance Based Restricted Stock Unit [Member]	Dec. 31, 2012 Additional Restricted Stock Units [Member]	Dec. 31, 2011 Additional Restricted Stock Units [Member]	Dec. 31, 2012 Restricted Stock [Member]	Dec. 31, 2011 Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Actual amount of RSUs earned based on cumulative earnings							60.00%
Target RSUs granted range						40.00%
Units outstanding	123,980	99,725	69,378
Performance cycle							3 years
Vesting period				3 years	3 years	3 years		3 years	3 years
Shares granted during period	58,775	54,825		35,265	32,894			23,510	21,931
Weighted average grant date fair value		$ 38.71		$ 38.82	$ 31.18			$ 38.82	$ 31.18
Compensation expense				$ 0.6	$ 0.1					$ 0.5	$ 0.1