Note 13 - Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Postretirement Health Coverage [Member]
Service cost	$ 0.1	$ 0.0	$ 0.1
Interest cost	0.2	0.3	0.3
Expected return on plan assets	0.0	0.0	0.0
Amortization of net actuarial loss (gain)	0.0	(0.1)	0.0
Net periodic benefit cost (credit)	0.3	0.2	0.4
Curtailment	0.0	0.0	0.0
Net benefit cost (credit)	0.3	0.2	0.4
UNITED STATES | Pension Plan [Member]
Service cost	0.0	0.0	0.0
Interest cost	0.0	0.1	0.0
Expected return on plan assets	0.0	0.0	0.0
Amortization of net actuarial loss (gain)	0.1	0.0	0.1
Net periodic benefit cost (credit)	0.1	0.1	0.1
Curtailment	0.0	0.0	0.0
Net benefit cost (credit)	0.1	0.1	0.1
Foreign Plan [Member] | Pension Plan [Member]
Service cost	0.0	0.0	0.1
Interest cost	0.2	0.3	0.3
Expected return on plan assets	(0.3)	(0.4)	(0.4)
Amortization of net actuarial loss (gain)	0.0	0.0	0.0
Net periodic benefit cost (credit)	(0.1)	(0.1)	0.0
Curtailment	0.0	0.0	(0.1)
Net benefit cost (credit)	$ (0.1)	$ (0.1)	$ (0.1)