Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2017	Apr. 30, 2016
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning			$ (14,022)
Other comprehensive income before reclassifications, net of tax			(51)
Amounts reclassified from accumulated other comprehensive income, net of tax			867
Net current-period other comprehensive income, net of tax	$ 189	$ 441	816	$ 599
Accumulated Other Comprehensive (Loss) Income, Balance, ending	(13,206)		(13,206)
Pension and Postretirement Health Benefits
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning			(13,867)
Other comprehensive income before reclassifications, net of tax			0
Amounts reclassified from accumulated other comprehensive income, net of tax			867
Net current-period other comprehensive income, net of tax			867
Accumulated Other Comprehensive (Loss) Income, Balance, ending	(13,000)		(13,000)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning			(155)
Other comprehensive income before reclassifications, net of tax			(51)
Amounts reclassified from accumulated other comprehensive income, net of tax			0
Net current-period other comprehensive income, net of tax			(51)
Accumulated Other Comprehensive (Loss) Income, Balance, ending	$ (206)		$ (206)