Employee Postretirement Benefits (Details) - Other Postretirement Benefit Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2015	Jul. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 108	$ 49	$ 216	$ 98
Interest cost	105	92	210	183
Amortization of actuarial losses	84	38	168	76
Net periodic benefit cost	$ 297	$ 179	$ 594	$ 357