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, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 51	$ 46	$ 152	$ 140
Interest cost	87	84	261	252
Amortization of actuarial losses	45	59	136	175
Net periodic benefit cost	$ 183	$ 189	$ 549	$ 567