Note 2 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total	$ (700,000)	$ 2,500,000	$ (700,000)
Foreign Currency Transaction Gain (Loss), before Tax, Total	(400,000)	700,000	(300,000)
Contract with Customer, Liability, Total	0
Inventory, Noncurrent, Total	3,833,000
Inventory, Net, Current and Noncurrent		22,000,000
Inventory Adjustments, Total	3,500,000	1,700,000
Allocated Share-based Compensation Expense, Total	$ 11,046,000	5,807,000	3,392,000
Number of Operating Segments	1
Number of Reportable Segments	1
Performance Shares [Member]
Allocated Share-based Compensation Expense, Total	$ 700,000	$ 800,000	$ 300,000
Minimum [Member]
Property, Plant and Equipment, Useful Life	5 years
Minimum [Member] | Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset				$ 20,000,000
Operating Lease, Liability, Total				30,000,000
Maximum [Member]
Property, Plant and Equipment, Useful Life	16 years
Maximum [Member] | Subsequent Event [Member] | Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset				23,000,000
Operating Lease, Liability, Total				$ 35,000,000
Other Noncurrent Assets [Member]
Inventory, Noncurrent, Total	$ 3,800,000
Accounts Receivable [Member] | Customer Concentration Risk [Member] | DePuy Mitek Inc [Member]
Concentration Risk, Percentage	75.00%	68.00%