Condensed Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Condensed Consolidated Statement of Other Comprehensive Income (Loss) [Abstract]
Net income	$ 7.5	$ 1.5	$ 10.0	$ 14.8
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	(2.7)	(0.3)	(3.9)	(0.6)
Pension liabilities adjustment	0.1	0	0.2	0.4
Net unrealized loss on available-for-sale securities	(0.2)	0.4	0	0.2
Reclassification of adjustment for gains included in net income [Abstract]
Foreign currency transaction adjustment (included in other income)	0	(0.1)		(0.1)
Realized gain on available-for-sale securities (included in trading gains, net)	0	0		(8.3)
Income tax expense from reclassification adjustments (included in income tax expense)	0	0	0	2.0
Reclassification adjustment for gains included in net income	0	(0.1)	0	(6.4)
Other comprehensive loss	(2.8)	0	(3.7)	(6.4)
Comprehensive income	$ 4.7	$ 1.5	$ 6.3	$ 8.4