Variable Interest Entities and Equity Method Investment, Variable Interest Entities (Details) - USD ($) $ in Thousands	3 Months Ended
	Nov. 02, 2019	Oct. 27, 2018	Jul. 31, 2019
Variable Interest Entity [Abstract]
Current assets	$ 41,290		$ 42,998
Total assets	55,416		51,810
Current liabilities	19,172		18,022
Total Ecology and Environment Inc. shareholder's equity	31,200		32,868
Noncontrolling interests shareholders' equity	996		907
Total shareholders' equity	32,196		33,775
Total liabilities and shareholders' equity	55,416		51,810
Total gross revenue of consolidated variable interest entities	22,213	$ 21,752
Variable Interest Entity [Member]
Variable Interest Entity [Abstract]
Current assets	3,226		3,549
Noncurrent assets	1,952		781
Total assets	5,178		4,330
Current liabilities	5,246		5,728
Noncurrent liabilities	7		12
Total liabilities	5,253		5,740
Total Ecology and Environment Inc. shareholder's equity	253		(708)
Noncontrolling interests shareholders' equity	(328)		(702)
Total shareholders' equity	(75)		(1,410)
Total liabilities and shareholders' equity	5,178		4,330
Total gross revenue of consolidated variable interest entities	2,700	$ 2,400
Restricted cash	$ 200		$ 200