9. Investment In and Advances to Affiliates (Details) - Siebert Brandford Shank Co LLC [Member] - USD ($)	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Total assets, including secured demand note of $1,200,000 due from Siebert	$ 32,104,000
Total liabilities, including purchase obligation of $1,971,000, advance payable of $100,000, and subordinated liabilities of $1,200,000 due to Siebert	15,724,000
Total members' capital	16,380,000
Regulatory minimum net capital requirement	250,000
Total revenues	13,969,000	$ 12,384,000
Net income (loss)	$ 495,000	$ 810,000