8. Investment In and Advances to Affiliates (Details) (SiebertBrandfordShankCoLLC, USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
SiebertBrandfordShankCoLLC
Total assets, including secured demand note of $1,200,000 due from Siebert	$ 31,634,000
Total liabilities, including subordinated liabilities of $1,200,000 due to Siebert	14,246,000
Total members capital	17,388,000
Regulatory minimum net capital requirement	250,000
Total revenues	7,735,000	3,995,000
Net income (loss)	$ 1,481,000	$ (1,229,000)