Annual report pursuant to Section 13 and 15(d)

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

v3.7.0.1
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, 2017
Mar. 31, 2016
Mar. 31, 2015
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 37,800 $ 36,471 $ 40,384
Cash [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 154 103  
U.S. companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 20,570 20,010  
International companies, Equity Securities [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 5,071 4,459  
Fixed income, Corporate bond funds, Intermediate-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 9,585 9,520  
Fixed income, Corporate bond funds, Short-term [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2,420 2,379  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 37,800 36,471  
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Cash [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 154 103  
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 20,570 20,010  
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 5,071 4,459  
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 9,585 9,520  
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 $ 2,420 $ 2,379