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Note 9 - Stockholders' Equity and Equity Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Apr. 30, 2019	Dec. 31, 2018	Apr. 30, 2018
Stock Repurchase Program, Number of Shares Authorized to be Repurchased						2,000,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 12.0		$ 12.0
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition			1 year 11 months 15 days
Share-based Compensation Arrangement by Share-based Payment Award, Award Requisite Service Period			1 year
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			52,783
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price			$ 18.11
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance	0		0
A 2016 Employee Plan [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased							1,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	1,998,884		1,998,884
A 2016 Director Plan [Member]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased					300,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	323,813		323,813
Share-based Payment Arrangement, Option [Member]
Stock Repurchased During Period, Shares			48,409	0
Stock Repurchased During Period, Value			$ 1.0
Treasury Stock Acquired, Average Cost Per Share			$ 20.52
Share-based Payment Arrangement, Option [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period			7 years
Share-based Payment Arrangement, Option [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period			10 years
Current Stock Awards [Member]
Share-based Payment Arrangement, Expense	$ 1.5	$ 1.1	$ 5.5	$ 5.2
Deferred Stock Units [Member]
Share-based Payment Arrangement, Expense	0.3	$ 0.1	0.5	$ 1.0
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	0.4		$ 0.4
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition			7 months 6 days
In Connection With Equity Compensation Programs [Member]
Stock Repurchase Program, Authorized Amount	10.0		$ 10.0
Stock Repurchased During Period, Shares			110,406	224,700
Stock Repurchased During Period, Value			$ 2.2	$ 5.4
Treasury Stock Acquired, Average Cost Per Share			$ 20.21	$ 24.15
Through The Open Market Repurchase Program [Member]
Stock Repurchased During Period, Shares			1,426,916	548,198
Stock Repurchased During Period, Value			$ 24.9	$ 13.2
Treasury Stock Acquired, Average Cost Per Share			$ 17.46	$ 24.07
Amended Credit Facility [Member]
Stock Repurchase Program, Authorized Amount	$ 32.0		$ 32.0