Stock-based compensation (Details Textual) (USD $)	3 Months Ended			6 Months Ended	0 Months Ended				3 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2013	Aug. 31, 2008 Director [Member]	Jul. 15, 2013 Director One [Member]	Apr. 12, 2013 Director One [Member]	Jan. 17, 2013 Director One [Member]	Jun. 30, 2013 Director Two [Member]	Mar. 31, 2013 Director Two [Member]	Dec. 31, 2012 Director Two [Member]
Share Based Compensation Arrangement By Share Based Payment Award Exercisable Date					Aug. 15, 2009
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Date					Aug. 15, 2013
Exercised, Weighted-Average Exercise Price				$ 0	$ 0.38
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	100,000		100,000	100,000
Class of Warrant or Right, Outstanding	30,000			30,000
Class of Warrant or Right, Exercise Price of Warrants or Rights	0.63			0.63
Common Stock Value To Be Issued	$ 12,500		$ 0	$ 12,500
Stock Issued During Period, Shares, New Issues	78,126	86,806	78,126			39,063	34,722	31,250	39,063	17,362	15,626
Stock Issued During Period Per Share Value Of New Issues	$ 0.16	$ 0.18	$ 0.20
Stock Issued During Period, Value, New Issues	$ 12,500	$ 15,625	$ 15,625
Warrants Issued Expire Period				July 2014
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted					25,000