Note 1 - Description of Business and Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Table Text Block]

	Year ended December 31,
(in thousands)	2018		2017		2016
Cash and cash equivalents	$	192,844	$	90,332	$	59,110
Restricted cash, non-current		100		200		200
Total cash, cash equivalents, and restricted cash shown in the statement of cash flows	$	192,944	$	90,532	$	59,310