Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Additional Information (Detail)

v3.8.0.1
Employee Benefit Plans - Additional Information (Detail)
 12 Months Ended
Mar. 31, 2018
USD ($)
$ / Employee
Mar. 31, 2017
USD ($)
Mar. 31, 2016
USD ($)
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 $ 30,385,000 $ 30,678,000  
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 5.00%    
Medical care trend year 2024    
Medical care cost trend rate decrements 0.50%    
Current portion of accrued postretirement benefit obligation $ 81,000 83,000  
Company contributions to the ESOP   0 $ 0
Stop loss coverage per employee for claims | $ / Employee 100    
Maximum aggregate stop loss coverage | $ / Employee 1,000    
Total plan amount $ 2,398,000    
Self-Insured medical plan liability 122,000 174,000  
Defined Contribution Plan 401K [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Contributions to defined contribution plan 805,000 873,000 866,000
Pension Plans, Defined Benefit [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Contributions expected during fiscal 2019 0    
Liability released through annuity purchase (890,000) (1,118,000)  
Annuities purchased (998,000) (1,246,000)  
Estimated net actuarial loss for pension plan 847,000    
Pension expense $ 57,000 $ 528,000 $ (49,000)
Weighted average discount rates used to develop net postretirement benefit cost 4.08% 3.93% 3.74%
Defined Contribution Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Contributions to defined contribution plan $ 284,000 $ 286,000 $ 315,000
Supplemental Executive Retirement Plan [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Pension expense 115,000 128,000 76,000
Pension expense related liability 582,000 493,000  
Current portion of the related liability included in accrued compensation 17,000 26,000  
Other Postretirement Benefit Plans [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Estimated net actuarial loss for pension plan 27,000    
Pension expense $ 63,000 $ 62,000 $ 69,000
Weighted average discount rates used to develop net postretirement benefit cost 3.23% 3.16% 3.11%