Stock-based compensation (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares, Outstanding at beginning of year	200,000	0
Shares, Granted	0	200,000
Shares, Expired and forfeited	(25,000)	0
Shares, Exercised	0	0
Shares, Outstanding at end of year	175,000	200,000	0
Shares, Exercisable	175,000
Weighted-Average Exercise Price, Outstanding at beginning of year	$ 0.17	$ 0
Weighted-Average Exercise Price, Granted		0.17
Weighted-Average Exercise Price, Expired and forfeited	0.17
Weighted-Average Exercise Price, Outstanding at end of year	0.17	$ 0.17	$ 0
Weighted-Average Exercise Price, Exercisable	$ 0.17
Remaining Contractual Term, Outstanding	3 years 4 months 17 days	4 years 4 months 17 days	4 years 4 months 17 days
Remaining Contractual Term, Expired and forfeited	3 years 4 months 17 days
Remaining Contractual Term, Exercisable	3 years 4 months 17 days