Segments and Entity-Wide Disclosures - Revenue, Profit (Loss) and Net Income (Loss) Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Revenue:
Total revenue	$ 960,606	$ 818,817	$ 2,604,144	$ 2,194,930
Segment profit:
Operating income (loss)	125,301	85,274	253,564	134,076
Less: Non-performance operating expenses
Selling and marketing	104,230	95,395	305,845	281,269
General and administrative	42,695	38,212	124,092	115,594
Amortization of intangible assets	5,529	3,837	16,586	11,083
Significant asset impairments and restructuring costs	5,355	6,359	11,696	16,679
Acquisition and integration costs	1,362	1,333	4,105	1,333
Add: Other non-performance financial items
Interest expense and other income (loss), net	(8,354)	(15,154)	(23,257)	(39,048)
Less: Provision for income taxes	30,198	19,280	57,204	503,695
Net income (loss)	86,749	50,840	173,103	(408,667)
Operating Segments
Segment profit:
Operating income (loss)	284,472	230,410	715,888	560,034
Operating Segments | Networking Platforms
Revenue:
Total revenue	796,068	677,451	2,113,609	1,765,166
Segment profit:
Operating income (loss)	230,610	181,603	542,391	396,995
Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	47,842	41,183	152,116	133,415
Segment profit:
Operating income (loss)	6,029	9,305	30,982	121,823
Operating Segments | Global Services
Revenue:
Total revenue	116,696	100,183	338,419	296,349
Segment profit:
Operating income (loss)	47,833	39,502	142,515	41,216
Converged Packet Optical
Revenue:
Total revenue	724,245		1,897,080
Converged Packet Optical | Operating Segments | Networking Platforms
Revenue:
Total revenue	724,245	592,892	1,897,080	1,548,189
Converged Packet Optical | Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	0		0
Converged Packet Optical | Operating Segments | Global Services
Revenue:
Total revenue	0		0
Packet Networking
Revenue:
Total revenue	71,823		216,529
Packet Networking | Operating Segments | Networking Platforms
Revenue:
Total revenue	71,823	84,559	216,529	216,977
Packet Networking | Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	0		0
Packet Networking | Operating Segments | Global Services
Revenue:
Total revenue	0		0
Platform Software and Services
Revenue:
Total revenue	37,312		114,139
Platform Software and Services | Operating Segments | Networking Platforms
Revenue:
Total revenue	0		0
Platform Software and Services | Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	37,312	36,818	114,139	117,347
Platform Software and Services | Operating Segments | Global Services
Revenue:
Total revenue	0		0
Blue Planet Automation Software and Services
Revenue:
Total revenue	10,530		37,977
Blue Planet Automation Software and Services | Operating Segments | Networking Platforms
Revenue:
Total revenue	0		0
Blue Planet Automation Software and Services | Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	10,530	4,365	37,977	16,068
Blue Planet Automation Software and Services | Operating Segments | Global Services
Revenue:
Total revenue	0		0
Maintenance Support and Training
Revenue:
Total revenue	65,936		196,002
Maintenance Support and Training | Operating Segments | Networking Platforms
Revenue:
Total revenue	0		0
Maintenance Support and Training | Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	0		0
Maintenance Support and Training | Operating Segments | Global Services
Revenue:
Total revenue	65,936	60,897	196,002	177,759
Installation and Deployment
Revenue:
Total revenue	39,802		111,746
Installation and Deployment | Operating Segments | Networking Platforms
Revenue:
Total revenue	0		0
Installation and Deployment | Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	0		0
Installation and Deployment | Operating Segments | Global Services
Revenue:
Total revenue	39,802	31,262	111,746	89,487
Consulting and Network Design
Revenue:
Total revenue	10,958		30,671
Consulting and Network Design | Operating Segments | Networking Platforms
Revenue:
Total revenue	0		0
Consulting and Network Design | Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	0		0
Consulting and Network Design | Operating Segments | Global Services
Revenue:
Total revenue	$ 10,958	$ 8,024	$ 30,671	$ 29,103