Note 4 - Fair Value Measurements (Details Textual) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Sep. 30, 2017	Dec. 31, 2017	Jun. 30, 2017	Aug. 01, 2016	Mar. 14, 2016	Nov. 03, 2014
Advanced Cell Diagnostics (ACD) [Member]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			$ 75.0	$ 50.0
Business Combination, Liabilities Arising from Contingencies, Amount Recognized					$ 37.0
Advanced Cell Diagnostics (ACD) [Member] \| Scenario, Forecast [Member]
Payment for Contingent Consideration Liability	$ 50.0
Zephyrus [Member]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			7.0	3.5
Business Combination, Liabilities Arising from Contingencies, Amount Recognized						$ 6.5
CyVek, Inc. [Member]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			35.0	$ 35.0
Business Combination, Liabilities Arising from Contingencies, Amount Recognized							$ 35.0
Payment for Contingent Consideration Liability		$ 35.0
Advance Cell Diagnostics (ACD), Zephyrus, and CyVek Inc.[Member]
Business Combination, Liabilities Arising from Contingencies, Amount Recognized			$ 78.5