Annual report pursuant to Section 13 and 15(d)

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

v3.19.1
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, 2019
Mar. 31, 2018
Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 38,416 $ 38,810 $ 37,800
Cash [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 87 98  
U.S. companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 15,130 20,663  
International companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 3,795 5,181  
Fixed income, Corporate bond funds, Long-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 19,404    
Fixed income, Corporate bond funds, Intermediate-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets   10,283  
Fixed income, Corporate bond funds, Short-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets   2,585  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 38,416 38,810  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 87 98  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 15,130 20,663  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | International companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 3,795 5,181  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed income, Corporate bond funds, Long-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 19,404    
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed income, Corporate bond funds, Intermediate-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets   10,283  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fixed income, Corporate bond funds, Short-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets   $ 2,585