Revenue from Contracts with Customers (Impact of ASC 606 on Income Statement) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	$ 334,689	$ 306,644
Cost of revenue	77,352	83,035
Gross margin	257,337	223,609
Sales and marketing	104,218	99,375
Research and development	60,782	63,972
General and administrative	37,864	35,020
Amortization of acquired intangible assets	5,936	7,821
Restructuring and other charges, net	18,493	105
Total operating expenses	227,293	206,293
Operating income	30,044	17,316
Interest Expense	10,276	10,047
Other income (expense), net	655	(798)
Income before income taxes	20,423	6,471
Benefit for income taxes	(562)	(7,406)
Net income	20,985	13,877
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	338,757	306,644
Cost of revenue	75,196
Gross margin	263,561
Sales and marketing	107,304
Research and development	60,782
General and administrative	37,864
Amortization of acquired intangible assets	5,936
Restructuring and other charges, net	18,493
Total operating expenses	230,379
Operating income	33,182
Interest Expense	10,276
Other income (expense), net	548
Income before income taxes	23,454
Benefit for income taxes	4,206
Net income	19,248
Software
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	293,243	265,190
Cost of revenue	43,760	46,616
Software | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	299,388	265,190
Cost of revenue	42,977
Support and cloud services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	187,921	145,672
Cost of revenue	31,197	34,502
Support and cloud services | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	125,483
Cost of revenue	30,630
License
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	105,322	119,518
Cost of revenue	12,563	12,114
License | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	173,905
Cost of revenue	12,347
Professional services
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	41,446	41,454
Cost of revenue	33,592	36,419
Professional services | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	39,369	$ 41,454
Cost of revenue	32,219
Accounting Standards Update 2014-09 | License
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue	65,000
Revenue On New And Renewal Bookings	$ 59,000