Leases (Lease Cost and Additional Information) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2021	Jan. 31, 2020
Leases [Abstract]
Amortization of ROU assets	$ 16,000	$ 44,000	$ 28,000	$ 152,000
Interest on lease liabilities	1,000	1,000	2,000	3,000
Operating lease expense	2,861,000	2,699,000	5,349,000	5,336,000
Short-term lease expense	255,000	878,000	502,000	1,741,000
Variable lease expense	1,190,000	1,016,000	2,154,000	2,009,000
Sublease income	(16,000)	0	(33,000)	0
Total lease expense	$ 4,307,000	$ 4,638,000	8,002,000	9,241,000
Operating leases - Operating cash outflows			5,050,000	5,725,000
Finance leases - Operating cash outflows			2,000	3,000
Finance leases - Financing cash outflows			28,000	300,000
ROU assets obtained in the exchange for lease liabilities (non-cash): operating leases			$ 25,663,000	$ 1,823,000