Goodwill and intangible assets (Details) - Schedule of intangible assets - USD ($) $ in Thousands	Jul. 31, 2016	Jul. 31, 2015
Goodwill and intangible assets (Details) - Schedule of intangible assets [Line Items]
Finite-lived intangible assets, Gross	$ 27,650	$ 27,838
Finite-lived intangible assets, Accumulated Amortization	(23,228)	(21,683)
Finite-lived intangible assets, Net	4,422	6,155
Patents [Member]
Goodwill and intangible assets (Details) - Schedule of intangible assets [Line Items]
Finite-lived intangible assets, Gross	11,027	11,028
Finite-lived intangible assets, Accumulated Amortization	(10,905)	(10,871)
Finite-lived intangible assets, Net	122	157
Customer Relationships [Member]
Goodwill and intangible assets (Details) - Schedule of intangible assets [Line Items]
Finite-lived intangible assets, Gross	12,122	12,243
Finite-lived intangible assets, Accumulated Amortization	(8,331)	(7,398)
Finite-lived intangible assets, Net	3,791	4,845
Website And Acquired Content [Member]
Goodwill and intangible assets (Details) - Schedule of intangible assets [Line Items]
Finite-lived intangible assets, Gross	1,011	1,020
Finite-lived intangible assets, Accumulated Amortization	(1,011)	(1,020)
Licensed Technology And Other [Member]
Goodwill and intangible assets (Details) - Schedule of intangible assets [Line Items]
Finite-lived intangible assets, Gross	485	518
Finite-lived intangible assets, Accumulated Amortization	(437)	(441)
Finite-lived intangible assets, Net	48	77
Trademarks [Member]
Goodwill and intangible assets (Details) - Schedule of intangible assets [Line Items]
Finite-lived intangible assets, Gross	3,005	3,029
Finite-lived intangible assets, Accumulated Amortization	(2,544)	(1,953)
Finite-lived intangible assets, Net	$ 461	$ 1,076