Note 9 - Stockholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
Feb. 08, 2021	Mar. 31, 2021	Mar. 31, 2020	Jan. 12, 2016	Jul. 28, 2015
Common Stock, Dividends, Per Share, Declared (in dollars per share)	$ 0.20	$ 0.20	$ 0.20
Stock Repurchase Program, Authorized Amount				$ 70.0	$ 15.0
Stock Repurchase Program, Remaining Authorized Repurchase Amount		$ 21.9

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration