Income taxes (Details 2) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Deferred taxes-current
Reserves for bad debts, inventories, and other accruals	$ 137,821	$ 120,740
Depreciation of property and equipment	(73,156)	(64,519)
Total deferred tax asset current	64,665	56,221
Deferred taxes - non-current
Depreciation of property and equipment	(237,635)	(230,478)
Total deferred tax liability non-current	$ (237,635)	$ (230,478)