Derivative Instruments (Details 3) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Derivatives not designated or not qualifying as hedging instruments
Foreign exchange forward contracts	$ 20	$ (24)	$ (54)	$ (174)
Statement of Comprehensive Income (Loss) Location	Net income (loss) resulting from foreign exchange transactions	Net income (loss) resulting from foreign exchange transactions	Net income (loss) resulting from foreign exchange transactions	Net income (loss) resulting from foreign exchange transactions

Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of foreign currency derivatives not designated as hedging instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

Name:	us-gaap_GainLossOnForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration