Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended			9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013		Jun. 30, 2012	Sep. 30, 2012
Numerator:
Net income	$ 35.1	$ 23.5	$ 62.2		$ 53.8	$ 62.2
Denominator:
Weighted average shares outstanding - basic	46.5	46.8	46.7		46.8	46.7
Effect of dilutive securities:
Equity compensation plans	0.6	0.6			0.6	0.7
Convertible preferred stock		0.1		[1]	0.1
Weighted average shares outstanding - diluted	47.1	47.5	47.4		47.5	47.4
Basic earnings per share (in dollars per share)	$ 0.75	$ 0.50	$ 1.33		$ 1.15	$ 1.33
Diluted earnings per share (in dollars per share)	$ 0.74	$ 0.49	$ 1.31		$ 1.13	$ 1.31

[1] Antidilutive