Note 13 - Stockholders' (Deficit) - Warrants (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number outstanding (in shares)	19,020,000	22,020,000	27,020,000
Weighted average remaining contractual life (Year)	354 days	1 year 21 days
Weighted average exercise price (in dollars per share)	$ 0.48	$ 0.45
Class of Warrant or Right, Exercisable (in shares)	19,020,000	22,020,000
Warrants exercisable, weighted average exercise price (in dollars per share)	$ 0.48	$ 0.45
Minimum [Member]
Range of exercise price (in dollars per share)	0.25	0.25
Maximum [Member]
Range of exercise price (in dollars per share)	$ 0.60	$ 0.60