Pension and Other Postretirement Benefits - Summary (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 106	$ 117
Interest expense	957	1,029
Expected return on plan assets	(740)	(1,121)
Amortization of prior service cost	10	10
Actuarial loss	521	456
Net periodic pension cost	854	491
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2	2
Interest expense	69	82
Amortization of prior service cost	(176)	(177)
Actuarial loss	94	109
Net periodic pension cost	$ (11)	$ 16