Note 8 - Long-term Debt and Credit Facility (Details Textual) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended		11 Months Ended	23 Months Ended
	Apr. 29, 2020	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2021	Feb. 28, 2023	Dec. 31, 2019	Mar. 12, 2018	Oct. 31, 2015
Long-term Debt, Total		$ 228,192	$ 228,192				$ 278,520
Payments of Financing Costs, Total			1,995	$ (0)
Long-term Debt, Fair Value		230,400	230,400				286,800
Derivative, Fixed Interest Rate								2.937%
A 2015 Interest Rate Swap [Member]
Derivative Asset, Notional Amount									$ 262,500
Derivative, Fixed Interest Rate									1.46%
A 2018 Interest Rate Swap [Member]
Derivative Asset, Notional Amount								$ 170,600
Derivative, Fixed Interest Rate								2.937%
Derivative, Amount of Hedged Item								$ 170,600
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Term Loan [Member]
Long-term Debt, Total		227,500	227,500				253,800
A 2015 Credit Facility [Member]
Debt Instrument, Face Amount									$ 650,000
Line of Credit Facility, Maximum Borrowing Capacity									350,000
Other Loans Payable, Total		700	700				800
Letters of Credit Outstanding, Amount		$ 31,600	$ 31,600
Long-term Line of Credit, Total							$ 24,000
Derivative, Amount of Hedged Item									$ 262,500
Credit Facility Maximum Consolidated Leverage Ratio		4.75	4.75
Credit Facility Actual Consolidated Leverage Ratio		2.31	2.31
Line of Credit Facility, Current Borrowing Capacity		$ 143,400	$ 143,400
Credit Facility Minimum Consolidated Fixed Charge Ratio		1.10	1.10
A 2015 Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Interest Rate, Effective Percentage		4.25%	4.25%
A 2015 Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Forecast [Member]
Debt Instrument, Basis Spread on Variable Rate					3.50%
A 2015 Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Forecast [Member] | Minimum [Member]
Debt Instrument, Basis Spread on Variable Rate						1.75%
A 2015 Credit Facility [Member] | London Interbank Offered Rate (LIBOR) [Member] | Forecast [Member] | Maximum [Member]
Debt Instrument, Basis Spread on Variable Rate						3.50%
A 2015 Credit Facility [Member] | Term Loan [Member]
Long-term Debt, Total		$ 245,000	$ 245,000
Debt Instrument, Interest Rate, Effective Percentage		5.23%	5.23%
A 2015 Credit Facility [Member] | Revolving Credit Facility [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 175,000	$ 175,000
Payments of Financing Costs, Total		2,000
Line Of Credit Facility, Unamortized Loan Costs		1,900
Interest Expense, Debt, Total		200
Repayments of Long-term Lines of Credit			24,000
Line of Credit Facility, Remaining Borrowing Capacity		251,700	251,700
A 2015 Credit Facility [Member] | Revolving Credit Facility [Member] | Up-front Lending Fees [Member]
Payments of Financing Costs, Total		1,500
A 2015 Credit Facility [Member] | Revolving Credit Facility [Member] | Third-party Arranging Fees and Expenses [Member]
Payments of Financing Costs, Total		500
A 2015 Credit Facility [Member] | Insurance Carries Collateral [Member]
Letters of Credit Outstanding, Amount		11,200	11,200
A 2015 Credit Facility [Member] | Working Performance Obligation [Member]
Letters of Credit Outstanding, Amount		$ 20,400	$ 20,400