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, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 21	$ 20	$ 43	$ 40
Interest cost	82	83	164	166
Amortization of actuarial losses	30	37	60	74
Amortization of unrecognized prior service cost (Credit)	(40)	(40)	(80)	(80)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 93	$ 100	$ 187	$ 200