Quarterly report pursuant to Section 13 or 15(d)

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

v3.3.0.814
Employee Benefit Plans - Components of Postretirement Benefit Cost (Income) and Pension Benefit Income (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Sep. 30, 2015
Sep. 30, 2014
Sep. 30, 2015
Sep. 30, 2014
Pension Plans, Defined Benefit [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 130 $ 137 $ 261 $ 273
Interest cost 359 358 718 717
Expected return on assets (795) (759) (1,590) (1,517)
Amortization of prior service benefit   1   2
Amortization of actuarial loss 294 145 587 290
Net pension benefit income and postretirement benefit cost (income) (12) (118) (24) (235)
Other Postretirement Benefit Plans [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 6 8 13 16
Amortization of prior service benefit   (27)   (53)
Amortization of actuarial loss 10 10 20 20
Net pension benefit income and postretirement benefit cost (income) $ 16 $ (9) $ 33 $ (17)