Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2020	Oct. 31, 2019
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning	$ (12,254)
Other comprehensive loss before reclassifications, net of tax	272
Amounts reclassified from accumulated other comprehensive income, net of tax	128
Net current-period other comprehensive income, net of tax	(400)	$ (227)
Accumulated Other Comprehensive (Loss) Income, Balance, ending	(11,854)
Pension and Postretirement Health Benefits
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning	(11,994)
Other comprehensive loss before reclassifications, net of tax	0
Amounts reclassified from accumulated other comprehensive income, net of tax	128
Net current-period other comprehensive income, net of tax	(128)
Accumulated Other Comprehensive (Loss) Income, Balance, ending	(11,866)
Cumulative Translation Adjustment
Accumulated Other Comprehensive (Loss) Income
Accumulated Other Comprehensive (Loss) Income, Balance, beginning	(260)
Other comprehensive loss before reclassifications, net of tax	272
Amounts reclassified from accumulated other comprehensive income, net of tax	0
Net current-period other comprehensive income, net of tax	(272)
Accumulated Other Comprehensive (Loss) Income, Balance, ending	$ 12