Pension and Other Postretirement Benefits (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Apr. 30, 2013
Apr. 30, 2012
Apr. 30, 2013
Apr. 30, 2012
Pension Plan
       
Defined Benefit Plans and Other Postretirement Benefit Plans        
Service Cost $ 437 $ 331 $ 1,313 $ 993
Interest Cost 386 405 1,158 1,213
Expected return on plan assets (377) (370) (1,132) (1,110)
Amortization of Prior service costs 4 4 11 11
Amortization of Other actuarial loss 221 79 663 238
Net periodic benefit cost 671 449 2,013 1,345
Postretirement Health Plan
       
Defined Benefit Plans and Other Postretirement Benefit Plans        
Service Cost 34 26 102 78
Interest Cost 24 27 72 79
Amortization of Net transition obligation 4 4 12 12
Amortization of Other actuarial loss 13 7 39 22
Net periodic benefit cost $ 75 $ 64 $ 225 $ 191