v3.26.1
Note 10 - Retirement Plans (Details Textual) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Defined Contribution Plan, Employer Discretionary Contribution Amount $ 0 $ 0  
Increase Decrease In Unfunded status (32,400)    
Defined Benefit Plan, Plan Assets, Period Increase (Decrease)   (2,500)  
Defined Benefit Plan, Benefit Obligation, Period Increase (Decrease)   29,900  
Defined Benefit Plan, Accumulated Benefit Obligation 203,000 203,800  
Defined Benefit Plan, Plan Assets, Amount 323,061 293,121 $ 288,949
Defined Benefit Plan, Benefit Obligation, Benefits Paid $ 10,926 $ 21,375  
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 100.00%    
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-Term Rate of Return on Plan Assets 6.95% 6.55% 6.15%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Change Due to Subsequent Interim Measurement, Weighted-Average Expected Long-Term Rate of Return on Plan Assets 7.30%    
Defined Benefit Plan, Benefit Obligation $ 214,919 $ 217,388 $ 236,507
Unfunded Deferred Compensation Plan [Member]      
Defined Benefit Plan, Benefit Obligation 4,200 3,400  
Employees’ Savings 401(k) Plan [Member]      
Defined Contribution Plan, Employer Discretionary Contribution Amount $ 3,200 2,800 $ 2,500
Diversified Mix of Return-seeking Investments [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 38.00%    
Fixed Income Investment [Member]      
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage 62.00%    
Lump Sum Payout [Member]      
Defined Benefit Plan, Benefit Obligation, Benefits Paid   $ 10,200