Employee Postretirement Benefits (Details) (Other Postretirement Benefit Plans, Defined Benefit [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 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	$ 98	$ 101
Interest cost	92	87	183	174
Amortization of actuarial losses	38	45	76	91
Net periodic benefit cost	$ 179	$ 183	$ 357	$ 366