Revenue from Contracts with Customers (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue	$ 295,486	$ 314,777	$ 920,626	$ 929,303
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenue	322,410	314,777	976,666	929,303
Subscription license
Disaggregation of Revenue [Line Items]
Revenue	53,705		168,762
Subscription support & cloud services
Disaggregation of Revenue [Line Items]
Revenue	90,159		250,811
Subscription Services
Disaggregation of Revenue [Line Items]
Revenue	143,864		419,573
Subscription Services | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenue	171,631	126,712	482,114	339,651
Perpetual support
Disaggregation of Revenue [Line Items]
Revenue	100,328		315,242
Perpetual support | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenue	99,664	121,127	312,453	379,007
Recurring Services
Disaggregation of Revenue [Line Items]
Revenue	244,192		734,815
Recurring Services | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenue	271,295	247,839	794,567	718,658
Perpetual license
Disaggregation of Revenue [Line Items]
Revenue	9,213		61,354
Perpetual license | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenue	10,644	25,780	63,661	82,604
Software
Disaggregation of Revenue [Line Items]
Revenue	253,405	273,619	796,169	801,262
Software | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenue	281,939	273,619	858,228	801,262
Professional services
Disaggregation of Revenue [Line Items]
Revenue	42,081	41,158	124,457	128,041
Professional services | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Revenue	$ 40,471	$ 41,158	$ 118,438	$ 128,041