Note 5 - Leases - Lease Cost and Other Information (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating lease cost (1)	[1]	$ 13.4	$ 11.8	$ 38.7	$ 35.9
Depreciation of finance lease assets (2)	[2]	3.1	4.0	6.2	10.1
Interest on finance lease liabilities (3)	[3]	0.2	0.4	0.5	1.2
Total lease cost		16.7	16.2	45.4	47.2
Operating cash outflows from operating leases		(13.4)	(10.8)	(39.0)	(34.4)
Operating cash outflows from finance leases		(0.2)	(0.4)	(0.5)	(1.2)
Financing cash outflows from finance leases		$ (8.6)	$ (6.9)	$ (13.0)	$ (11.4)
Weighted-average remaining lease term in years - operating leases (Year)		9 years 3 months 18 days	9 years 6 months	9 years 3 months 18 days	9 years 6 months
Weighted-average remaining lease term in years - finance leases (Year)		2 years 7 months 6 days	2 years 9 months 18 days	2 years 7 months 6 days	2 years 9 months 18 days
Weighted-average discount rate - operating leases		4.10%	3.90%	4.10%	3.90%
Weighted-average discount rate - finance leases		4.00%	4.50%	4.00%	4.50%

[1] Included in "Cost of revenues" and "Selling, general and administrative" expenses in the accompanying condensed consolidated statements of operations

[2] Included in "Depreciation and amortization of fixed assets" in the accompanying condensed consolidated statements of operations

[3] Included in "Interest expense" in the accompanying condensed consolidated statements of operations