Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Fair Values of Company's Pension Plan Assets by Asset Category (Detail)

v3.21.1
Employee Benefit Plans - Fair Values of Company's Pension Plan Assets by Asset Category (Detail) - Pension Plans, Defined Benefit [Member] - USD ($)
$ in Thousands
Mar. 31, 2021
Mar. 31, 2020
Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 42,536 $ 39,243 $ 38,416
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 42,536 39,243  
Cash [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 79 82  
Cash [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 79 82  
U.S. companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 11,202 9,409  
U.S. companies, Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 11,202 9,409  
International companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2,700 2,327  
International companies, Equity Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2,700 2,327  
Fixed income, Corporate bond funds, Long-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 28,555 27,425  
Fixed income, Corporate bond funds, Long-term [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 28,555 $ 27,425