XML 72 R47.htm IDEA: XBRL DOCUMENT v3.19.3
Net Periodic Benefit Cost (Components of net periodic pension cost and net periodic postretirement benefit cost) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Pension Plans, Defined Benefiit        
Defined Benefit Plan Disclosure [Line Items]        
Service costs $ 248 $ 267 $ 515 $ 536
Interest cost 3,676 3,880 7,375 7,765
Expected return on plan assets (3,972) (4,605) (7,945) (9,242)
Net amortization 571 589 1,140 1,178
Net periodic pension (benefit) cost 523 131 1,085 237
Other Postretirement Benefit Plans, Defined Benefit        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 20 28 40 57
Net amortization (40) (12) (80) (24)
Net periodic pension (benefit) cost $ (20) $ 16 $ (40) $ 33