Note 7 - Goodwill and Intangible Assets (Details Textual) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Amortization of Intangible Assets, Total	$ 5.3	$ 5.0
Customer Lists [Member]
Intangible Assets (Excluding Goodwill), Disposed of	0.9
Trade Names [Member]
Intangible Assets (Excluding Goodwill), Disposed of	$ 1.4

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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