8. Investment In and Advances to Affiliates (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 SiebertBrandfordShankCoLLC	Sep. 30, 2012 SiebertBrandfordShankCoLLC
Total assets, including secured demand note of $1,200,000 due from Siebert			$ 20,897,000
Total liabilities, including subordinated liabilities of $1,200,000 due to Siebert			5,554,000
Total members capital			15,343,000
Regulatory minimum net capital requirement			250,000
Total revenues	7,962,000	6,731,000	16,991,000	20,785,000
Net income (loss)	$ 1,562,000	$ 380,000	$ (380,000)	$ 1,812,000