Employee Postretirement Benefits Employee Postretirement Benefits (Details) - Other Postretirement Benefit Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 7	$ 21	$ 14	$ 43
Interest cost	79	82	158	164
Amortization of actuarial losses	32	30	64	60
Amortization of unrecognized prior service cost (Credit)	(40)	(40)	(80)	(80)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 78	$ 93	$ 156	$ 187