Note 7 - Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Beginning balance	$ 45.3	$ 35.4	$ 32.0
Additions based on tax positions related to the current year	13.9	11.6	10.3
(Reductions) based on tax positions taken in prior years	(2.4)		(3.2)
Additions based on tax positions taken in prior years		5.4
Reductions due to settlements		(2.4)	(0.4)
Reductions due to lapse of applicable statute of limitations	(4.6)	(4.7)	(3.3)
Ending balance	$ 52.2	$ 45.3	$ 35.4

Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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