(Purchase Price Allocation and Estimated Useful Lives) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jan. 31, 2018	Jul. 31, 2017
Business Acquisition [Line Items]
Goodwill	$ 343,248	$ 141,851
Cyence, Inc.
Business Acquisition [Line Items]
Acquired assets, net of assumed liabilities	7,470
Trademarks	2,500
Goodwill	201,079
Total purchase price	260,349
Cyence, Inc. | Developed technology
Business Acquisition [Line Items]
Finite lived assets acquired	$ 28,400
Estimated Useful Lives	5 years
Cyence, Inc. | Customer contracts and related relationships
Business Acquisition [Line Items]
Finite lived assets acquired	$ 17,700
Estimated Useful Lives	5 years
Cyence, Inc. | Order backlog
Business Acquisition [Line Items]
Finite lived assets acquired	$ 3,200
Estimated Useful Lives	2 years
Cyence, Inc. | Trademarks
Business Acquisition [Line Items]
Estimated Useful Lives	7 years
ISCS
Business Acquisition [Line Items]
Acquired assets, net of assumed liabilities	$ 4,551
Deferred tax assets, net	171
Goodwill	96,410
Total purchase price	154,932
ISCS | Developed technology
Business Acquisition [Line Items]
Finite lived assets acquired	$ 43,300
Estimated Useful Lives	4 years
ISCS | Customer contracts and related relationships
Business Acquisition [Line Items]
Finite lived assets acquired	$ 7,000
Estimated Useful Lives	9 years
ISCS | Order backlog
Business Acquisition [Line Items]
Finite lived assets acquired	$ 3,500
Estimated Useful Lives	4 years