8. Share-based payments (Details 6) - Nonemployee Common stock warrants - Service and performance conditions [Member] - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Number of Warrants
Nonvested, Beginning	1,880,000	2,000,000
Vested		(120,000)
Forfeited	(1,880,000)
Nonvested, Ending		1,880,000
Weighted-average Grant Date Fair Value
Nonvested, Beginning	$ 0.99	$ 0.99
Vested	0.99	0.99
Nonvested, Ending		$ 0.99