Net income (loss) per common share - Basic and Diluted Earnings (Details 1) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Basic earnings per share
Net loss per share from continuing operations, amount	$ (2,931,462)	$ (161,829)	$ (4,147,618)	$ (5,817,376)
Net loss per share from continuing operations, number of shares	123,976,208	108,772,921	123,571,357	93,838,855
Net loss per share from continuing operations, per share	$ (0.02)		$ (0.03)	$ (0.06)
Net income per share from discontinued operations, number of shares	123,976,208	108,772,921	123,571,357	93,838,855
Net income per share from discontinued operations, per share				$ 0.08
Net income (loss)	$ (2,931,462)	$ (303,006)	$ (4,147,618)	$ 1,595,267
Diluted earnings per share
Net loss per share from continuing operations, amount	$ (2,931,462)	$ (161,829)	$ (4,147,618)	$ (5,817,376)
Net loss per share from continuing operations, per share	$ (0.02)		$ (0.03)	$ (0.06)
Net income per share from discontinued operations, number of shares	123,976,208	108,772,921	123,571,357	104,974,243
Net Income Per Share [Member]
Basic earnings per share
Net loss per share from continuing operations, amount				$ (5,817,376)
Net loss per share from continuing operations, number of shares				93,838,855
Net loss per share from continuing operations, per share				$ (0.06)
Net income per share from discontinued operations, amount				$ 7,412,643
Net income per share from discontinued operations, number of shares				93,838,855
Net income per share from discontinued operations, per share				$ 0.08
Effect of dilutive securities
Warrants, number of shares				11,135,388
Diluted earnings per share
Net loss per share from continuing operations, amount				$ (5,817,376)
Net loss per share from continuing operations, number of shares				104,974,243
Net loss per share from continuing operations, per share				$ (0.06)
Net income per share from discontinued operations, amount				$ 7,412,643
Net income per share from discontinued operations, number of shares				104,974,243
Net income per share from discontinued operations, per share				$ 0.07