Note 13 - Retirement Benefit Plans - Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total recognized in other comprehensive (income) loss	$ 1.3	$ 0.5	$ (1.7)
Pension Plan [Member] | UNITED STATES
Prior service cost	0.0	0.0	0.0
Net actuarial loss (gain)	(0.0)	(0.1)	(0.0)
Amortization of net actuarial (loss) gain	(0.1)	0.0	(0.1)
Total recognized in other comprehensive (income) loss	(0.1)	0.1	(0.1)
Total recognized in net benefit cost (credit) and other comprehensive loss (income)	0.0	0.2	0.0
Pension Plan [Member] | Foreign Plan [Member]
Prior service cost	0.1	0.0	0.1
Net actuarial loss (gain)	(1.6)	(0.4)	1.2
Amortization of net actuarial (loss) gain	0.0	0.0	0.0
Total recognized in other comprehensive (income) loss	1.7	0.4	(1.1)
Total recognized in net benefit cost (credit) and other comprehensive loss (income)	1.6	0.3	(1.2)
Postretirement Health Coverage [Member]
Prior service cost	0.0	0.0	0.0
Net actuarial loss (gain)	0.3	0.1	0.5
Amortization of net actuarial (loss) gain	0.0	0.1	0.0
Total recognized in other comprehensive (income) loss	(0.3)	0.0	(0.5)
Total recognized in net benefit cost (credit) and other comprehensive loss (income)	$ 0.0	$ 0.2	$ (0.1)