Quarterly report pursuant to Section 13 or 15(d)

Employee Benefit Plans - Components of Postretirement Benefit Cost and Pension Cost (Benefit) (Detail)

v3.6.0.2
Employee Benefit Plans - Components of Postretirement Benefit Cost and Pension Cost (Benefit) (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Pension Plans, Defined Benefit [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 151 $ 130 $ 451 $ 391
Interest cost 362 360 1,087 1,078
Expected return on assets (718) (795) (2,155) (2,385)
Amortization of actuarial loss 337 293 1,013 880
Net pension cost (benefit) and postretirement benefit cost 132 (12) 396 (36)
Other Postretirement Benefit Plans [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 5 7 19 20
Amortization of actuarial loss 11 10 30 30
Net pension cost (benefit) and postretirement benefit cost $ 16 $ 17 $ 49 $ 50