Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning	$ (10,292)
Other comprehensive loss before reclassifications, net of tax	(74)
Amounts reclassified from accumulated other comprehensive income, net of tax	181
Net current-period other comprehensive income (loss), net of tax	107	$ 255
Accumulated Other Comprehensive (Loss) Income, Balance, ending	(10,185)
Pension and Postretirement Health Benefits
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning	(10,327)
Other comprehensive loss before reclassifications, net of tax	0
Amounts reclassified from accumulated other comprehensive income, net of tax	181
Net current-period other comprehensive income (loss), net of tax	181
Accumulated Other Comprehensive (Loss) Income, Balance, ending	(10,146)
Cumulative Translation Adjustment
Accumulated Other Comprehensive Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning	35
Other comprehensive loss before reclassifications, net of tax	(74)
Amounts reclassified from accumulated other comprehensive income, net of tax	0
Net current-period other comprehensive income (loss), net of tax	(74)
Accumulated Other Comprehensive (Loss) Income, Balance, ending	$ (39)