Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenue	$ 778,527	$ 646,135
Products and services at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	646,404
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	132,123
Converged Packet Optical
Disaggregation of Revenue [Line Items]
Total revenue	548,997
Packet Networking
Disaggregation of Revenue [Line Items]
Total revenue	71,569
Platform Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	41,598
Blue Planet Automation Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	14,974
Maintenance Support and Training
Disaggregation of Revenue [Line Items]
Total revenue	61,277
Installation and Deployment
Disaggregation of Revenue [Line Items]
Total revenue	30,622
Consulting and Network Design
Disaggregation of Revenue [Line Items]
Total revenue	9,490
Networking Platforms | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	620,566	496,033
Networking Platforms | Operating Segments | Products and services at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	620,566
Networking Platforms | Operating Segments | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	0
Networking Platforms | Operating Segments | Converged Packet Optical
Disaggregation of Revenue [Line Items]
Total revenue	548,997	427,401
Networking Platforms | Operating Segments | Packet Networking
Disaggregation of Revenue [Line Items]
Total revenue	71,569	68,632
Networking Platforms | Operating Segments | Platform Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	0
Networking Platforms | Operating Segments | Blue Planet Automation Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	0
Networking Platforms | Operating Segments | Maintenance Support and Training
Disaggregation of Revenue [Line Items]
Total revenue	0
Networking Platforms | Operating Segments | Installation and Deployment
Disaggregation of Revenue [Line Items]
Total revenue	0
Networking Platforms | Operating Segments | Consulting and Network Design
Disaggregation of Revenue [Line Items]
Total revenue	0
Software and Software-Related Services | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	56,572	53,487
Software and Software-Related Services | Operating Segments | Products and services at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	22,272
Software and Software-Related Services | Operating Segments | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	34,300
Software and Software-Related Services | Operating Segments | Converged Packet Optical
Disaggregation of Revenue [Line Items]
Total revenue	0
Software and Software-Related Services | Operating Segments | Packet Networking
Disaggregation of Revenue [Line Items]
Total revenue	0
Software and Software-Related Services | Operating Segments | Platform Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	41,598	44,136
Software and Software-Related Services | Operating Segments | Blue Planet Automation Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	14,974	9,351
Software and Software-Related Services | Operating Segments | Maintenance Support and Training
Disaggregation of Revenue [Line Items]
Total revenue	0
Software and Software-Related Services | Operating Segments | Installation and Deployment
Disaggregation of Revenue [Line Items]
Total revenue	0
Software and Software-Related Services | Operating Segments | Consulting and Network Design
Disaggregation of Revenue [Line Items]
Total revenue	0
Global Services | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue	101,389	96,615
Global Services | Operating Segments | Products and services at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	3,566
Global Services | Operating Segments | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	97,823
Global Services | Operating Segments | Converged Packet Optical
Disaggregation of Revenue [Line Items]
Total revenue	0
Global Services | Operating Segments | Packet Networking
Disaggregation of Revenue [Line Items]
Total revenue	0
Global Services | Operating Segments | Platform Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	0
Global Services | Operating Segments | Blue Planet Automation Software and Services
Disaggregation of Revenue [Line Items]
Total revenue	0
Global Services | Operating Segments | Maintenance Support and Training
Disaggregation of Revenue [Line Items]
Total revenue	61,277	55,958
Global Services | Operating Segments | Installation and Deployment
Disaggregation of Revenue [Line Items]
Total revenue	30,622	30,016
Global Services | Operating Segments | Consulting and Network Design
Disaggregation of Revenue [Line Items]
Total revenue	$ 9,490	$ 10,641