Commitments and contingencies (Details 3) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Analysis of the leased property under capital leases
Total capital leases, gross	$ 1,865,908	$ 882,246
Less: Accumulated depreciation	(662,082)	(257,615)
Total capital leases, net	1,203,826	624,631
Future minimum rental payments under capital leases
2014	509,083
2015	371,305
2016	123,179
2017	10,968
2018	3,620
Total minimum lease payments	1,018,155
Net minimum lease payments	1,018,155
Less: Amounts representing interest payments	(68,559)
Present value of net minimum lease payments	949,596
Computer hardware
Analysis of the leased property under capital leases
Total capital leases, gross	1,607,602	882,246
Computer software
Analysis of the leased property under capital leases
Total capital leases, gross	$ 258,306