Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Summary of Increase (Decrease) in Accumulated Other Comprehensive Loss, Net of Income Tax (Detail)

v3.19.1
Employee Benefit Plans - Summary of Increase (Decrease) in Accumulated Other Comprehensive Loss, Net of Income Tax (Detail) - USD ($)
$ in Thousands
 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]      
Total $ 348 $ (1,668) $ (2,493)
Pension Plans, Defined Benefit [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Net actuarial loss (gain) arising during the year 1,080 (794)  
Reclassification of stranded tax effects related to the Tax Act   1,771  
Amortization of actuarial loss (712) (788)  
Total 368 189  
Other Postretirement Benefit Plans [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Net actuarial loss (gain) arising during the year 1 (57)  
Reclassification of stranded tax effects related to the Tax Act   57  
Amortization of actuarial loss (21) (29)  
Total $ (20) $ (29)