Variable Interest Entities - Additional Disclosures (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2015 USD ($) VIE	Mar. 31, 2014 USD ($)	Mar. 31, 2015 USD ($) VIE	Mar. 31, 2014 USD ($)	Sep. 30, 2014 VIE
Variable Interest Entity [Line Items]
Number of VIEs formed					3
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entities, Income | $	$ 9.3	$ 2.0	$ 19.9	$ 4.2
Variable Interest Entities, Expense | $	$ 6.0	$ 0.7	$ 17.0	$ 1.4
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Number of VIEs	2		2
Grupo Finmart [Member] | VIE B and C [Member]
Variable Interest Entity [Line Items]
Percent of cash flows received			100.00%
Grupo Finmart [Member] | VIE A [Member]
Variable Interest Entity [Line Items]
Percent of cash flows received			50.00%