Note 7 - Leases (Details Textual) $ in Millions		1 Months Ended		12 Months Ended
	Dec. 31, 2011 USD ($) ft²	Feb. 28, 2019 ft²	Jun. 30, 2012 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Operating Lease, Expense | $				$ 4.9	$ 5.1	$ 5.1
Sublease Income | $				$ 0.5	$ 0.5	$ 0.4
CALIFORNIA
Percentage of Annual Rent Increment		3.00%
Area of Subleased Property (Square Foot) | ft²		12,429
Lease Agreement One [Member]
Area of Leased Property (Square Foot) | ft²	65,656
Percentage of Annual Rent Increment	3.00%
Lease Agreement Two [Member]
Area of Leased Property (Square Foot) | ft²			29,470
Percentage of Annual Rent Increment			3.00%
Letters of Credit Outstanding, Amount | $	$ 1.5		$ 1.1
Lease Option To Extend Term (Year)			5 years