Note 8 - Goodwill and Intangible Assets - Changes in Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Balance	$ 235.1	$ 221.7
Balance, accumulated impairment losses	(40.0)	(39.0)
Balance, net	195.1	182.7
Additions	0.0	15.6
Foreign currency fluctuations	14.4	(2.2)
Foreign currency fluctuations, accumulated impairment losses	1.7	1.0
Foreign currency fluctuations, net	12.7	(3.2)
Balance	249.5	235.1
Balance, accumulated impairment losses	(41.7)	(40.0)
Balance, net	$ 207.8	$ 195.1