Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income, Balance, beginning	$ (5,035)
Other comprehensive income, before reclassifications, net of tax	(75)
Amounts reclassified from accumulated other comprehensive income, net of tax	57
Net current-period other comprehensive income, net of tax	(18)	169
Accumulated Other Comprehensive Income, Balance, ending	(5,053)
Unrealized Gain (Loss) on Marketable Securities
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income, Balance, beginning	86
Other comprehensive income, before reclassifications, net of tax	(8)
Amounts reclassified from accumulated other comprehensive income, net of tax	0
Net current-period other comprehensive income, net of tax	(8)
Accumulated Other Comprehensive Income, Balance, ending	78
Pension and Postretirement Health Benefits
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income, Balance, beginning	(5,608)
Other comprehensive income, before reclassifications, net of tax	0
Amounts reclassified from accumulated other comprehensive income, net of tax	(57)
Net current-period other comprehensive income, net of tax	57
Accumulated Other Comprehensive Income, Balance, ending	(5,551)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive Income, Balance, beginning	487
Other comprehensive income, before reclassifications, net of tax	(67)
Amounts reclassified from accumulated other comprehensive income, net of tax	0
Net current-period other comprehensive income, net of tax	(67)
Accumulated Other Comprehensive Income, Balance, ending	$ 420