Note 8 - Goodwill and Intangible Assets - Intangible Assets and Related Accumulated Amortization (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Cost	$ 2,209.6	$ 2,175.3
Accumulated amortization	(893.3)	(776.4)
Net	$ 1,316.3	$ 1,398.9
Technology [Member]
Weighted average useful life (Year)	7 years	7 years
Cost	$ 519.8	$ 519.2
Accumulated amortization	(330.2)	(291.9)
Net	$ 189.6	$ 227.3
Marketing [Member]
Weighted average useful life (Year)	16 years	16 years
Cost	$ 261.6	$ 265.3
Accumulated amortization	(105.4)	(94.3)
Net	$ 156.2	$ 171.0
Contract-based [Member]
Weighted average useful life (Year)	6 years	6 years
Cost	$ 5.0	$ 5.0
Accumulated amortization	(5.0)	(5.0)
Net	$ 0.0	$ 0.0
Customer [Member]
Weighted average useful life (Year)	13 years	13 years
Cost	$ 947.8	$ 901.2
Accumulated amortization	(328.2)	(278.0)
Net	$ 619.6	$ 623.2
Database [Member]
Weighted average useful life (Year)	19 years	19 years
Cost	$ 475.4	$ 484.6
Accumulated amortization	(124.5)	(107.2)
Net	$ 350.9	$ 377.4