Stock-based compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2012
Outstanding at beginning of year, Shares	150,000
Granted, Shares	0
Expired and forfeited, Shares	(50,000)
Exercised, Shares	0
Outstanding at end of year, Shares	100,000
Exercisable, Shares	100,000
Outstanding at beginning of year, Weighted-Average Exercise Price	$ 0.36
Granted, Weighted-Average Exercise Price	$ 0
Expired and forfeited, Weighted-Average Exercise Price	$ 0.3275
Exercised, Weighted-Average Exercise Price	$ 0
Outstanding at end of year, Weighted-Average Exercise Price	$ 0.38
Exercisable, Weighted-Average Exercise Price	$ 0.38
Remaining Contractual Term, Outstanding	7 months 13 days
Exercisable, Remaining Contractual Term	7 months 13 days
Outstanding, Aggregate Fair Value	30,120
Exercisable, Aggregate Fair Value	30,120