Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Additional Information (Detail)

v3.19.1
Employee Benefit Plans - Additional Information (Detail)
 12 Months Ended
Mar. 31, 2019
USD ($)
$ / Employee
Mar. 31, 2018
USD ($)
Mar. 31, 2017
USD ($)
Defined Benefit Plan Disclosure [Line Items]      
Employee's years of service and average earnings Five highest consecutive calendar years of compensation in the ten-year period preceding retirement    
Accumulated benefit obligation $ 30,380,000 $ 30,385,000  
Contribution equal to employee salary deferral 100.00%    
Employer contribution description Matching contributions equal to 100% of the first 3% of an employee's salary deferral and 50% of the next 2% percent of an employee's salary deferral    
Contribution next to employee salary deferral 3.00%    
Contribution for additional employee salary deferral 50.00%    
Contribution additional next to employee salary deferral 2.00%    
Share of the medical premium cost for family coverage $ 4,000    
Share of the medical premium cost for single coverage 2,000    
Share of the medical premium both family and single coverage for regular retirees $ 1,000    
Medical care cost trend rate 4.50%    
Medical care trend year 2024    
Medical care cost trend rate decrements 0.50%    
Current portion of accrued postretirement benefit obligation $ 78,000 81,000  
Company contributions to the ESOP     $ 0
Stop loss coverage per employee for claims | $ / Employee 100    
Maximum aggregate stop loss coverage | $ / Employee 1,000    
Total plan amount $ 2,399,000    
Self-Insured medical plan liability 150,000 122,000  
Defined Contribution Plan 401K [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Contributions to defined contribution plan $ 1,135,000 $ 805,000 873,000
Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Target Plan Asset Allocations 50.00% 65.00%  
Debt Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Target Plan Asset Allocations 50.00% 35.00%  
Pension Plans, Defined Benefit [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Contributions expected during fiscal 2020 $ 0    
Liability released through annuity purchase 1,589,000 $ 890,000  
Annuities purchased 1,718,000 998,000  
Estimated net actuarial loss for pension plan 969,000    
Pension expense $ (305,000) $ 57,000 $ 528,000
Weighted average discount rates used to develop net postretirement benefit cost 3.95% 4.08% 3.93%
Defined Contribution Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Contributions to defined contribution plan $ 325,000 $ 284,000 $ 286,000
Supplemental Executive Retirement Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Pension expense 97,000 115,000 128,000
Pension expense related liability 662,000 582,000  
Current portion of the related liability included in accrued compensation 0 17,000  
Other Postretirement Benefit Plans [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Estimated net actuarial loss for pension plan 28,000    
Pension expense $ 53,000 $ 63,000 $ 62,000
Weighted average discount rates used to develop net postretirement benefit cost 3.63% 3.23% 3.16%