Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Changes in Company's Benefit Obligation, Plan Assets and Funded Status for Plan (Detail)

v3.20.1
Employee Benefit Plans - Changes in Company's Benefit Obligation, Plan Assets and Funded Status for Plan (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Pension Plans, Defined Benefit [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligation at beginning of year $ 34,149 $ 34,441  
Service cost 496 468  
Interest cost 1,290 1,339 $ 1,423
Actuarial loss (gain) 2,368 462  
Benefit payments (1,100) (972)  
Liability released through annuity purchase (1,420) (1,589)  
Projected benefit obligation at end of year 35,783 34,149 34,441
Change in fair value of plan assets      
Fair value of plan assets at beginning of year 38,416 38,810  
Employer contribution   30  
Actual return on plan assets 3,347 2,266  
Benefit payments (1,100) (972)  
Annuities purchased (1,420) (1,718)  
Fair value of plan assets at end of year 39,243 38,416 38,810
Funded status      
Funded status at end of year 3,460 4,267  
Amount recognized in the Consolidated Balance Sheets 3,460 4,267  
Other Postretirement Benefit Plans [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Projected benefit obligation at beginning of year 682 723  
Interest cost 22 25 26
Actuarial loss (gain) (3) 2  
Benefit payments (67) (68)  
Projected benefit obligation at end of year 634 682 $ 723
Change in fair value of plan assets      
Employer contribution 67 68  
Benefit payments (67) (68)  
Funded status      
Funded status at end of year (634) (682)  
Amount recognized in the Consolidated Balance Sheets $ (634) $ (682)