Employee Postretirement Benefits (Details) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 49	$ 51	$ 147	$ 152
Interest cost	91	87	274	261
Amortization of actuarial losses	38	45	114	136
Net periodic benefit cost	$ 178	$ 183	$ 535	$ 549