Note 4 - Business Combination, Contingent Consideration and Disposal of Branches - Assets Acquired and Liabilities Assumed (Details) - USD ($)			12 Months Ended
	Sep. 11, 2020	Dec. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Deferred tax liability		$ 340,000
Goodwill			$ 11,673,000	$ 5,153,000	$ 5,153,000
Payments to Acquire Businesses, Gross			4,945,000	387,000
Initial purchase price			$ 4,945,000	$ 387,000
Winslow Targets [Member]
Cash		1,111,000
Cash deposits with clearing organizations		207,000
Securities owned at fair value		1,111,000
Receivables from broker dealers and clearing organizations		49,000
Forgivable loans receivable		91,000
Other receivables, net		113,000
Prepaid expenses		432,000
Fixed assets, net		80,000
Intangible assets, net		4,400,000
Operating lease assets		1,823,000
Other assets		12,000
Total assets acquired		9,429,000
Securities sold, not yet purchased at fair value		203,000
Accrued commissions and payroll payable		390,000
Accounts payable and accrued expenses		188,000
Operating lease liabilities		1,823,000
Deferred tax liability		1,196,000
Other		215,000
Total liabilities assumed		4,015,000
Net identifiable assets acquired		5,414,000
Goodwill		2,680,000
Total Purchase price		8,094,000
Intangible assets, net		4,400,000
Payments to Acquire Businesses, Gross		3,200,000
Additional consideration payable (net operating capital)		873,000
Earnout (contingent consideration)		4,021,000
Total purchase price		8,094,000
Initial purchase price		3,200,000
Additional consideration payable		873,000
Total purchase price		8,094,000
Winslow Targets [Member] | Customer Relationships [Member]
Customer relationships		4,100,000
Winslow Targets [Member] | Brand Name [Member]
Customer relationships		300,000
United Advisor Acquisition [Member]
Cash		16,000
Prepaid expenses		12,000
Intangible assets, net		2,025,000
Total assets acquired		2,172,000
Total liabilities assumed		433,000
Net identifiable assets acquired		1,739,000
Goodwill		4,803,000
Total Purchase price		6,542,000
Intangible assets, net		2,025,000
Payments to Acquire Businesses, Gross	$ 2,790,000
Additional consideration payable (net operating capital)	210,000
Earnout (contingent consideration)	3,542,000
Total purchase price	6,542,000
Cash deposits with clearing organizations		33,000
Other receivables, net		86,000
Accounts payable and accrued expenses		7,000
Other		86,000
Initial purchase price	2,790,000
Additional consideration payable	210,000
Total purchase price	$ 6,542,000
United Advisor Acquisition [Member] | Customer Relationships [Member]
Customer relationships		1,960,000
United Advisor Acquisition [Member] | Brand Name [Member]
Customer relationships		$ 65,000