Note 5 - Leases - Lease Cost and Other Information (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating lease cost (1)	[1]	$ 12.9	$ 12.0	$ 25.2	$ 24.1
Depreciation of finance lease assets (2)	[2]	1.4	3.3	3.1	6.1
Interest on finance lease liabilities (3)	[3]	0.1	0.4	0.3	0.8
Total lease cost		14.4	15.7	28.6	31.0
Operating cash outflows from operating leases		(12.0)	(11.1)	(25.6)	(23.6)
Operating cash outflows from finance leases		(0.1)	(0.4)	(0.3)	(0.8)
Financing cash outflows from finance leases		$ (2.5)	$ (2.5)	$ (4.4)	$ (4.5)
Weighted-average remaining lease term in years - operating leases (Year)		9 years 6 months	9 years 7 months 6 days	9 years 6 months	9 years 7 months 6 days
Weighted-average remaining lease term in years - finance leases (Year)		2 years 2 months 12 days	2 years 9 months 18 days	2 years 2 months 12 days	2 years 9 months 18 days
Weighted-average discount rate - operating leases		4.10%	4.00%	4.10%	4.00%
Weighted-average discount rate - finance leases		3.40%	4.50%	3.40%	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