4. Revenue Recognition (Details) - USD ($)	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Principal transactions	$ 2,941,000	$ 109,000
Commissions and fees	2,674,000	1,183,000
Margin interest, marketing and distribution fees	2,535,000	1,080,000
Advisory fees	16,000	5,000
Interest and dividends	11,000	2,000
Total revenues	8,177,000	2,379,000
Principal transactions
Principal transactions	572,000	109,000
Principal transactions \| Assets acquired from StockCross
Principal transactions	2,369,000	0
Commissions and fees
Commissions and fees	1,955,000	1,183,000
Commissions and fees \| Assets acquired from StockCross
Commissions and fees	719,000	0
Margin interest, marketing and distribution fees
Margin interest, marketing and distribution fees	2,328,000	1,080,000
Margin interest, marketing and distribution fees \| Assets acquired from StockCross
Margin interest, marketing and distribution fees	$ 207,000	$ 0

Amount of fees and commissions from financial services and banking activities and correspondent clearing. Includes fees from depositor accounts, credit cards, merchant discounts, and fiduciary and trust activities, guarantee fees, investment advisory, management, and administrative fees, transfer agent fees, and insurance commissions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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Amount of revenue from providing investment advisory, asset management and administrative services, including, but not limited to, distribution and shareholder services, accounting, tax, legal, regulatory filing, share registration, and shareholder correspondence activities.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 225
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 940
-SubTopic 320
-Section 45
-Paragraph 5
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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