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, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Revenue:
Total revenue	$ 818,817	$ 728,719	$ 2,194,930	$ 2,057,238
Segment profit:
Operating income (loss)	85,274	81,999	134,076	158,923
Less: Non-performance operating expenses
Selling and marketing	95,395	86,739	281,269	260,292
General and administrative	38,212	35,569	115,594	106,423
Significant asset impairments and restructuring costs	6,359	2,203	16,679	8,874
Amortization of intangible assets	3,837	3,837	11,083	29,368
Acquisition and integration costs	1,333	0	1,333	0
Add: Other non-performance financial items
Interest expense and other income (loss), net	(15,154)	(14,263)	(39,048)	(45,322)
Less: Provision for income taxes	19,280	7,726	503,695	11,704
Net income (loss)	50,840	60,010	(408,667)	101,897
Operating Segments
Segment profit:
Operating income (loss)	230,410	210,347	560,034	563,880
Operating Segments | Networking Platforms
Revenue:
Total revenue	677,451	592,347	1,765,166	1,653,778
Segment profit:
Operating income (loss)	181,603	159,649	396,995	423,859
Operating Segments | Networking Platforms | Converged Packet Optical
Revenue:
Total revenue	592,892	510,226	1,548,189	1,433,137
Operating Segments | Networking Platforms | Packet Networking
Revenue:
Total revenue	84,559	82,121	216,977	220,641
Operating Segments | Software and Software-Related Services
Revenue:
Total revenue	41,183	42,251	133,415	119,347
Segment profit:
Operating income (loss)	9,305	11,133	41,216	116,637
Operating Segments | Software and Software-Related Services | Software Platforms
Revenue:
Total revenue	14,307	18,395	56,427	48,587
Operating Segments | Software and Software-Related Services | Software-Related Services
Revenue:
Total revenue	26,876	23,856	76,988	70,760
Operating Segments | Global Services
Revenue:
Total revenue	100,183	94,121	296,349	284,113
Segment profit:
Operating income (loss)	39,502	39,565	121,823	23,384
Operating Segments | Global Services | Maintenance Support and Training
Revenue:
Total revenue	60,897	57,902	177,759	171,133
Operating Segments | Global Services | Installation and Deployment
Revenue:
Total revenue	31,262	27,397	89,487	84,011
Operating Segments | Global Services | Consulting and Network Design
Revenue:
Total revenue	$ 8,024	$ 8,822	$ 29,103	$ 28,969