Segment and Geographic Information - Summary of Revenue and Profit Attributable to Our Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2020	Dec. 28, 2019
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	$ 429,050	$ 356,110
Operating costs	86,830	87,405
Gross margin	342,220	268,705
Sales and marketing	124,725	107,604
General and administrative	49,528	44,557
Restructuring and other charges, net	247	14,034
Intangibles amortization	12,814	13,576
Operating income	90,338	30,425
Interest expense	(11,518)	(12,098)
Other income (expense), net	(1,413)	704
Income before income taxes	77,407	19,031
Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	429,050	356,110
Operating costs	138,521	135,939
Gross margin	290,529	220,171
Unallocated
Segment Reporting Revenue Reconciling Item [Line Items]
Sales and marketing	109,726	100,152
General and administrative	27,400	26,919
Restructuring and other charges, net	247	14,034
Intangibles amortization	12,814	13,576
Stock-based compensation	46,088	27,936
Other unallocated operating expenses	3,916	7,129
Software Products | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	393,420	314,366
Operating costs	105,401	102,192
Gross margin	288,019	212,174
Professional Services | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	35,630	41,744
Operating costs	33,120	33,747
Gross margin	$ 2,510	$ 7,997