Derivative Instruments (Details 2) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2019	Apr. 30, 2018
Derivatives not designated or not qualifying as hedging instruments
Foreign exchange forward contracts	$ 80		$ 254	$ 1
Statement of Comprehensive Loss Location	Net loss resulting from foreign exchange transactions	Net loss resulting from foreign exchange transactions	Net loss resulting from foreign exchange transactions	Net loss resulting from foreign exchange transactions

Description of where the net gain (loss) on foreign currency derivatives are reported in the statement of income or other statement of financial performance.

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)(1)
-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
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (a)(2),(b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(n)(7))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration