Note 9 - Fair Value Measurements - Discounted Cash Flow Assumptions (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2016
Time-to-liquidity (months) (Month)	2 years	2 years
Minimum [Member]
Discount rate	4.20%	4.30%
Maximum [Member]
Discount rate	9.20%	9.30%