Note 13 - Sales and Service Revenue and Cost of Sales and Services - Sales and Service Revenue and Cost of Sales and Service Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2024	Jan. 31, 2023	Jan. 31, 2024	Jan. 31, 2023
Revenue	$ 116	$ 47,931	$ 224	$ 105,223
Cost of revenues	(97)	(33,361)	(187)	(76,795)
Sale of Inventory [Member]
Revenue	0	47,836	0	105,045
Cost of revenues	0	(33,282)	0	(76,647)
Toll Processing Services [Member]
Revenue	116	95	224	178
Cost of revenues	$ (97)	$ (79)	$ (187)	$ (148)