Share-Based Compensation (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2012	Mar. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total share-based compensation cost	$ 1.1	$ 1.3	$ 2.3	$ 2.5
Total income tax benefit recognized	0.4	0.5	0.9	1.0
Total unrecognized compensation cost related to share-based compensation arrangements	7.8		7.8
Remaining weighted-average period for recognition of total unrecognized compensation cost, years			1.9
Non-vested shares outstanding	486,908		486,908
Stock Option Plans [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax compensation expense	0	0.1	0	0.2
Performance-Accelerated Restricted Share Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax compensation expense	1.0	1.0	2.0	2.0
Non-Employee Directors Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Pretax compensation expense	$ 0.1	$ 0.2	$ 0.2	$ 0.3