Segment information (Schedule of Geographic Information about Revenues) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 31,177,616	$ 29,377,682	$ 55,576,988	$ 49,980,465
China (including Hong Kong) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	16,745,956	14,772,662	27,627,991	27,592,602
Asia, Others [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	3,674,631	2,345,866	7,108,620	3,464,946
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	8,065,607	7,459,918	15,467,649	11,806,378
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	2,355,550	4,719,437	4,775,500	7,016,240
South America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	126,358		291,366
Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	175,976	27,690	219,398	48,190
Others [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenue	$ 33,538	$ 52,109	$ 86,464	$ 52,109