Note 5 - Goodwill and Other Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill, balance as of the beginning of the period	$ 128,752	$ 128,752
Goodwill acquired during the period	0	0
Goodwill, balance as of the end of the period	128,752	128,752
UNITED STATES
Goodwill, balance as of the beginning of the period	123,883	123,883
Goodwill acquired during the period	0	0
Goodwill, balance as of the end of the period	123,883	123,883
Europe [Member]
Goodwill, balance as of the beginning of the period	4,239	4,239
Goodwill acquired during the period	0	0
Goodwill, balance as of the end of the period	4,239	4,239
JAPAN
Goodwill, balance as of the beginning of the period	630	630
Goodwill acquired during the period	0	0
Goodwill, balance as of the end of the period	$ 630	$ 630