Note 10 - Debt (Details Textual) - USD ($) $ in Thousands					1 Months Ended	3 Months Ended	12 Months Ended
		Feb. 18, 2020	Dec. 11, 2017	Jun. 19, 2014	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Long-term Debt, Total							$ 145,014
Amortization of Debt Issuance Costs							466	$ 531
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	[1]						5,948
Credit and Security Agreement with KeyBank [Member]
Debt Issuance Costs, Net, Total				$ 5,800			$ 1,300	$ 1,800
Line of Credit Facility, Interest Rate at Period End							3.31%	4.31%
Effective LIBOR Rate							1.81%	2.56%
Interest Expense, Debt, Total							$ 5,400	$ 5,300
Debt Instrument, Term			5 years	5 years
Payments of Debt Issuance Costs			$ 1,800		$ 700
Amortization of Debt Issuance Costs					$ 500	$ 1,000
Line of Credit Facility, Percentage of Capital Stock of Foreign Subsidiaries Collateralized Security			65.00%
LIBOR Additional Rate			1.00%
Credit and Security Agreement with KeyBank [Member] | Term Loan [Member]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months							$ 5,900
Credit and Security Agreement with KeyBank [Member] | Subsequent Event [Member] | Term Loan [Member]
Repayments of Long-term Debt, Total		$ 8,200
Credit and Security Agreement with KeyBank [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate							1.50%	1.75%
Credit and Security Agreement with KeyBank [Member] | London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate			1.375%
Credit and Security Agreement with KeyBank [Member] | London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate			2.75%
Credit and Security Agreement with KeyBank [Member] | Fed Funds Effective Rate Overnight Index Swap Rate [Member]
Debt Instrument, Basis Spread on Variable Rate			0.50%
Credit and Security Agreement with KeyBank [Member] | LIBOR With Maturity of One Month [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate			0.375%
Credit and Security Agreement with KeyBank [Member] | LIBOR With Maturity of One Month [Member] | Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate			1.75%
Credit and Security Agreement with KeyBank [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Remaining Borrowing Capacity							$ 43,000	$ 75,000
Line of Credit Facility, Maximum Borrowing Capacity			$ 75,000	$ 50,000
Credit and Security Agreement with KeyBank [Member] | Term Loan [Member]
Long-term Debt, Total							113,000	116,000
Long-term Line of Credit, Total							$ 32,000	$ 0
Debt Instrument, Face Amount			$ 125,000	145,000
Credit and Security Agreement with KeyBank [Member] | Delayed Draw Term Loan ("DDTL") [Member]
Debt Instrument, Face Amount				$ 70,000

[1] The $5.9 million of scheduled principal payments for 2020 noted in the table above was paid in full on February 18, 2020, as part of the above-mentioned $8.2 million voluntary prepayment made in connection with the amendment to the Credit Agreement.