Segment and Geographic Information - Summary of Revenue and Profit Attributable to Our Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 28, 2020	Mar. 31, 2021	Mar. 28, 2020
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	$ 461,785	$ 359,603	$ 890,836	$ 715,713
Operating costs	89,448	83,027	176,278	170,432
Gross margin	372,337	276,576	714,558	545,281
Sales and marketing	129,178	107,438	253,903	215,042
General and administrative	60,805	33,629	110,333	78,186
Restructuring and other charges, net	469	18,242	716	32,276
Intangibles amortization	14,767	14,167	27,581	27,743
Operating income	101,690	50,025	192,029	80,450
Interest and debt premium expense	(12,925)	(32,618)	(24,444)	(44,716)
Other expense, net	(2,408)	(1,629)	(3,821)	(925)
Income before income taxes	86,357	15,778	163,764	34,809
Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	461,785	359,603	890,836	715,713
Operating costs	142,449	128,337	280,970	264,276
Gross margin	319,336	231,266	609,866	451,437
Unallocated
Segment Reporting Revenue Reconciling Item [Line Items]
Sales and marketing	115,873	100,292	225,599	200,444
General and administrative	31,487	27,795	58,887	54,714
Restructuring and other charges, net	469	18,242	716	32,276
Intangibles amortization	14,767	14,167	27,581	27,743
Stock-based compensation	44,740	20,484	90,828	48,420
Other unallocated operating expenses	10,310	261	14,226	7,390
Software Products | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	421,767	324,080	815,188	638,446
Operating costs	109,310	94,912	214,711	197,104
Gross margin	312,457	229,168	600,477	441,342
Professional Services | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	40,018	35,523	75,648	77,267
Operating costs	33,139	33,425	66,259	67,172
Gross margin	$ 6,879	$ 2,098	$ 9,389	$ 10,095