Note 2 - Revenue (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 21,219,000	$ 16,050,000	$ 55,596,000	$ 44,386,000
UNITED STATES
Revenue from Contract with Customer, Including Assessed Tax	$ 5,735,000	2,876,000	$ 19,034,000	11,615,000
Blood Donor Screening Services [Member]
Revenue from Contract with Customer, Including Assessed Tax		93,000		1,700,000
Blood Donor Screening Services [Member] | UNITED STATES
Revenue from Contract with Customer, Including Assessed Tax		$ 93,000		$ 1,700,000