Note 17 - Regulatory Requirements (Details Textual) $ in Millions	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Ratio of Indebtedness to Net Capital	0.48	0.57
Broker-Dealer, Net Capital, Total	$ 22.5	$ 29.8
Broker-Dealer, Excess Net Capital, 1500 Percent, Aggregate Indebtedness Standard, Total	21.5	28.7
Broker-Dealer, Minimum Net Capital Required, Aggregate Indebtedness Standard, Total	$ 1.0	$ 1.1
Maximum [Member]
Ratio of Indebtedness to Net Capital	15

Amount of net capital in excess of minimum required net capital, calculated under Aggregate Indebtedness Standard.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

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Minimum amount of net capital required to be maintained by broker-dealer and its subsidiary, calculated under Aggregate Indebtedness Standard.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

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Amount of net capital of broker-dealer.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher SEC
-Name Rule 15c3-1
-Number 240
-Section 15c3-1

Indebtedness divided by net capital.

No definition available.

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