Segment Information - Summary of Segment Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Segment revenues:
Total revenues	$ 439,968	$ 382,059
Segment operating expense	(260,440)	(230,700)
Operating income	179,528	151,359
Unallocated share-based compensation expense	(40,654)	(31,574)
Unallocated amortization expense	0	(275)
Unallocated interest expense	(29,488)	(24,162)
Unallocated other income, net	89	3,393
Income before income taxes	150,129	130,590
Depreciation expense	2,595	1,691
Operating Segments
Segment revenues:
Segment operating expense	(219,786)	(198,851)
Operating income	220,182	183,208
Unallocated Corporate Expenses
Segment revenues:
Segment operating expense	(44,331)	(40,568)
Operating income	(44,331)	(40,568)
Depreciation expense	18	12
Scores
Segment revenues:
Total revenues	235,675	192,112
Scores | Operating Segments
Segment revenues:
Total revenues	235,675	192,112
Segment operating expense	(31,904)	(23,458)
Operating income	203,771	168,654
Depreciation expense	125	81
Software
Segment revenues:
Total revenues	204,293	189,947
Software | Operating Segments
Segment revenues:
Total revenues	204,293	189,947
Segment operating expense	(143,551)	(134,825)
Operating income	60,742	55,122
Depreciation expense	2,452	1,598
Professional services
Segment revenues:
Total revenues	18,282	21,279
Professional services | Scores | Operating Segments
Segment revenues:
Total revenues	0	0
Professional services | Software | Operating Segments
Segment revenues:
Total revenues	18,282	21,279
On-premises and SaaS software
Segment revenues:
Total revenues	186,011	168,668
On-premises and SaaS software | Scores | Operating Segments
Segment revenues:
Total revenues	0	0
On-premises and SaaS software | Software
Segment revenues:
Total revenues	186,011	168,668
On-premises and SaaS software | Software | Operating Segments
Segment revenues:
Total revenues	186,011	168,668
Scores
Segment revenues:
Total revenues	235,675	192,112
Scores | Scores | Operating Segments
Segment revenues:
Total revenues	235,675	192,112
Scores | Software | Operating Segments
Segment revenues:
Total revenues	$ 0	$ 0