Condensed Consolidated Statement of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Condensed Consolidated Statement of Other Comprehensive Income (Loss) [Abstract]
Net income	$ 13.0us-gaap_ProfitLoss	$ 7.5us-gaap_ProfitLoss	$ 22.4us-gaap_ProfitLoss	$ 10.0us-gaap_ProfitLoss
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustment	(0.8)	(2.7)	(1.1)	(3.9)
Pension liabilities adjustment	0	0.1	0	0.1
Net unrealized gain or loss on available-for-sale securities	2.3	(0.2)	3.4	0
Reclassification of adjustments included in net income [Abstract]
Periodic pension costs (included in compensation and benefits)	0	0	0	0.1
Reclassification adjustment for gains included in net income	0	0	0	0.1
Other comprehensive income (loss)	1.5	(2.8)	2.3	(3.7)
Comprehensive income	$ 14.5	$ 4.7	$ 24.7	$ 6.3

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Reclassification adjustments for gains (losses) included in net income

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments, of (increase) decrease in accumulated other comprehensive (income) loss related to pension and other postretirement defined benefit plans.

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Amount before tax of reclassification adjustment from accumulated other comprehensive (income) loss related to net period benefit cost (credit) for pension and other postretirement defined benefit plans.

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Amount after tax, before reclassification adjustments, of unrealized holding gain (loss) on available-for-sale securities.

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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