Segment and Geographic Information - Summary of Revenue and Profit Attributable to Our Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	$ 457,721	$ 429,050
Operating costs	95,118	86,830
Gross margin	362,603	342,220
Sales and marketing	125,476	124,725
General and administrative	51,940	49,528
Restructuring and other charges, net	33,991	247
Intangibles amortization	14,977	12,814
Operating income	62,178	90,338
Interest and debt premium expense	(12,986)	(11,518)
Other income (expense), net	6,184	(1,413)
Income before income taxes	55,376	77,407
Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	457,721	429,050
Operating costs	153,011	138,521
Gross margin	304,710	290,529
Unallocated
Segment Reporting Revenue Reconciling Item [Line Items]
Sales and marketing	112,395	109,726
General and administrative	34,177	27,400
Restructuring and other charges, net	33,991	247
Intangibles amortization	14,977	12,814
Stock-based compensation	45,942	46,088
Other unallocated operating expenses	1,050	3,916
Software Products | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	413,593	393,420
Operating costs	116,028	105,401
Gross margin	297,565	288,019
Professional Services | Operating Segments
Segment Reporting Revenue Reconciling Item [Line Items]
Revenue	44,128	35,630
Operating costs	36,983	33,120
Gross margin	$ 7,145	$ 2,510