Note 10 - Options and Warrants to Purchase Common Stock - Summary of the Vesting Periods of Options (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Stock options granted (in shares)	35,810,289	3,771,488
Vesting Period 1 [Member]
Stock options granted (in shares)	350,000
Vesting Period 2 [Member]
Stock options granted (in shares)	300,000
Vesting Period 3 [Member]
Stock options granted (in shares)	100,000
Vesting Period 4 [Member]
Stock options granted (in shares)	140,000
Vesting Period 5 [Member]
Stock options granted (in shares)	6,875,000
Vesting Period 6 [Member]
Stock options granted (in shares)	545,289
Vesting Period 7 [Member]
Stock options granted (in shares)	27,500,000