Pension and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	$ 360	$ 459
Interest cost	436	388
Expected return on plan assets	(429)	(382)
Amortization of Prior service costs	3	3
Amortization of Other actuarial loss	78	222
Net periodic benefit cost	448	690
Postretirement Health Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	30	34
Interest cost	29	24
Amortization of Net transition obligation	4	4
Amortization of Prior service costs	(1)	0
Amortization of Other actuarial loss	7	13
Net periodic benefit cost	$ 69	$ 75