Basis of Statement Presentation Revenue Recognition (Details) - Payments In Advance - USD ($)	9 Months Ended
Apr. 30, 2020	Jul. 31, 2019
Deferred Revenue Arrangement
Liability for Payments in Advance	$ 362,000	$ 259,000
Payments in Advance, Revenue Recognized	$ 174,000

Amount of deferred income and obligation to transfer product and service to customer for which consideration has been received or is receivable, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(5))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_DeferredRevenueCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant