Income taxes (Details 4) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Operating loss carryforwards
Valuation allowance	$ 29,416,464	$ 29,238,264
Federal
Operating loss carryforwards
Net operating loss carryforwards	70,400,000
State, primarily New York State
Operating loss carryforwards
Net operating loss carryforwards	$ 71,300,000