Note 5 - Goodwill - Goodwill Activity (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance, goodwill	$ 1,062,102	$ 888,224	$ 826,476
Additions, goodwill	0	173,878	0
Impairments, goodwill	0	0	0
Final purchase price adjustments, goodwill	21,185		61,748
Balance, goodwill	$ 1,083,287	$ 1,062,102	$ 888,224

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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