Commitments and Contingencies - Contigent Consideration for Acquisitions (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Business Acquisition, Contingent Consideration [Line Items]
Accounts payable and other accrued liabilities - contingent consideration, fair value	$ 5.5	$ 9.6
Business Combination, Contingent Consideration, Liability	5.5	9.6
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	(1.8)	8.2	2.1
Forward Insight Commodities Acquisition [Member]
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Contingent Consideration, Liability	0.3
Business Combination, Consideration, Including Contingent Consideration	0.5
Tradewire Acquisition [Member] [Member]
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Contingent Consideration, Liability	1.8
Business Combination, Consideration, Including Contingent Consideration	3.3
Tradewire Acquisition [Member] [Member] | Tradewire Acquisition [Member] [Member]
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Consideration Transferred		5.6
Coffee Network Acquisition [Member]
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Consideration, Including Contingent Consideration	0.3
Hencorp Acquisition [Member]
Business Acquisition, Contingent Consideration [Line Items]
Business Combination, Contingent Consideration, Liability	3.3
Business Combination, Consideration, Including Contingent Consideration	8.3
Contingent Consideration [Member]
Business Acquisition, Contingent Consideration [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Period Increase (Decrease)	(2.3)	2.6
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	$ (2.3)	$ 2.6	$ 2.0