Commitments and Contingencies Commitments and Contingencies - Contingencies and Litigation (Details) (USD $)	3 Months Ended
	Dec. 31, 2012
Sentinel Appeal Cash Deposit	$ 8,000,000
Excess segregated funds invested	21,900,000
Loss Contingency, Loss in Period	1,500,000
Loss Contingency, Settlement Agreement, Consideration	250,000
Pre and Post Transfers of Funds related to Sentinel	15,500,000
Customer Segregated Transfers of Funds Pursuant to Safe Harbor	1,100,000
Excess segregated funds returned	15,500,000
Minimum [Member]
Excess segregated funds returned	4,000,000
Maximum [Member]
Excess segregated funds returned	$ 6,000,000