Contingencies (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Sep. 30, 2011
Loss Contingencies [Line Items]
Maximum potential exposure to credit loss in the event of nonperformance	$ 152.9	$ 169.8
Letters of Credit, Maturity Term - Maximum	3 years
Collateral Held, Fair Value	$ 51.7
Pending or Threatened Litigation, Stanford Financial Group [Member]
Loss Contingencies [Line Items]
Lawsuits Naming Entity as Defendant, number	2
Pending or Threatened Litigation, Overdraft Fees [Member]
Loss Contingencies [Line Items]
Lawsuits Naming Entity as Defendant, number	2