Note 15 - Long-term Debt and Credit Arrangements (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Long-Term Debt, Current Maturities, Total	$ 8,735	$ 8,700	$ 8,727
Long-Term Debt, Excluding Current Maturities, Total	290,549	331,647	331,191
Interest Expense, Total	3,575	5,372
The Credit Agreement [Member]
Letters of Credit Outstanding, Amount	$ 32,900
Consolidated Leverage Ratio, Actual	2.58
Consolidated Leverage Ratio, Covenant Maximum	3.00
Consolidated Interest Coverage Ratio, Actual	6.07
Debt Instrument, Covenant, Minimum Consolidated Interest Coverage Ratio	4.00
The Credit Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	2.00%
Debt Instrument, Interest Rate, Effective Percentage	3.01%
The Credit Agreement [Member] | Base Rate [Member]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Debt Instrument, Interest Rate, Effective Percentage	4.50%
The Credit Agreement [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Remaining Borrowing Capacity	$ 242,100
Proceeds from Lines of Credit, Total	0
The Credit Agreement [Member] | Term Loan [Member]
Repayments of Debt	60,900
Long-Term Debt, Current Maturities, Total	7,500	7,500	7,500
Long-Term Debt, Excluding Current Maturities, Total	$ 53,400	121,900	116,300
The 2.75% Convertible Notes [Member]
Debt Instrument, Interest Rate, Stated Percentage	2.75%
Long-Term Debt, Gross	$ 230,000	202,000	$ 207,400
Interest Expense, Total	0	1,700
The 2.75% Convertible Notes [Member] | Other (Income) Expense [Member]
Amortization of Debt Discount (Premium)	$ 300	$ 300