Other Income (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other Income
Interest income	$ 83,416	$ 117,680	$ 84,199
Interest expense	(308,389)
Foreign currency exchange gain (loss)	242,564	(37,276)	542,108
Other	2,921	(805)	2,605
Total other income	$ 20,512	$ 79,599	$ 628,912