Commitments and Contingencies - Narrative (Details)	12 Months Ended
	Sep. 30, 2016 USD ($) Letter_of_credit	Sep. 30, 2015 USD ($) Letter_of_credit
Loss Contingencies [Line Items]
Deferred rent	$ 65,000	$ 33,000
Rent expense under operating leases	3,794,000	3,947,000
Sublease income under operating subleases	$ 142,000	$ 139,000
Number of letters of credit | Letter_of_credit	3	2
Pending And Threatened Litigation | Professional Fees
Loss Contingencies [Line Items]
Litigation and FINRA related expenses	$ 2,472,000	$ 2,057,000
Pending And Threatened Litigation | Accounts Payable and Accrued Expenses
Loss Contingencies [Line Items]
Accrued litigation liability	832,000	817,000
Letter of Credit
Loss Contingencies [Line Items]
Maximum borrowing capacity	$ 354,000	$ 218,000