Commitments and Contingencies - Contingencies and Litigation (Details) (USD $)	9 Months Ended
Jun. 30, 2013
Excess segregated funds returned	$ 15,500,000
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
Maximum [Member]
Excess segregated funds returned	6,000,000
Minimum [Member]
Excess segregated funds returned	$ 4,000,000

The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration