Future minimum capital lease payments (Details) (USD $)	Dec. 31, 2013
Future minimum capital lease payments
Future minimum capital lease payments in 2014	$ 815,184
Future minimum capital lease payments in 2015	611,388
Total future minimum lease payments	1,426,572
Less amount representing interest (at 9.9%)	121,823
Present value of net minimum capital lease payments	1,304,749
Less current installments of obligations under capital leases	717,870
Obligations under capital leases, excluding current installments	$ 586,879