Pension and Other Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	$ 361	$ 417	$ 721	$ 876
Interest cost	435	384	871	772
Expected return on plan assets	(429)	(373)	(858)	(755)
Amortization of Prior service costs	4	4	7	7
Amortization of Other actuarial loss	78	220	156	442
Net periodic benefit cost	449	652	897	1,342
Postretirement Health Plan
Defined Benefit Plans and Other Postretirement Benefit Plans
Service cost	30	34	60	68
Interest cost	29	24	58	48
Amortization of Net transition obligation	4	4	8	8
Amortization of Prior service costs	(2)	0	(3)	0
Amortization of Other actuarial loss	8	13	15	26
Net periodic benefit cost	$ 69	$ 75	$ 138	$ 150