Note 3 - Acquisitions (Details Textual) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
	Sep. 05, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Payments to Acquire Businesses, Net of Cash Acquired		$ 253,193	$ 10,634	$ 253,193
Trevigen Inc. [Member]
Payments to Acquire Businesses, Net of Cash Acquired	$ 10,600
Trevigen Inc. [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life	10 years
Trevigen Inc. [Member] | Customer Relationships [Member]
Finite-Lived Intangible Asset, Useful Life	12 years
Trevigen Inc. [Member] | Trade Names [Member]
Finite-Lived Intangible Asset, Useful Life	1 year 182 days