Segment Information - Schedule of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2026	Mar. 31, 2025	Mar. 31, 2026	Mar. 31, 2025
Segment revenues:
Total revenues	$ 691,677	$ 498,735	$ 1,203,636	$ 938,703
Segment operating expense	(289,212)	(253,087)	(567,122)	(513,527)
Operating income	402,465	245,648	636,514	425,176
Unallocated share-based compensation expense	(45,310)	(41,704)	(89,579)	(82,358)
Unallocated interest expense, net	(44,579)	(31,378)	(86,585)	(60,866)
Unallocated other expense, net	(1,857)	(1,254)	(1,969)	(1,165)
Income before income taxes	356,029	213,016	547,960	363,145
Operating Segments
Segment revenues:
Segment operating expense	(196,607)	(170,441)	(382,099)	(345,896)
Operating income	495,070	328,294	821,537	592,807
Unallocated Corporate Expenses
Segment revenues:
Segment operating expense	(47,295)	(40,942)	(95,444)	(85,273)
Scores
Segment revenues:
Total revenues	474,973	297,039	779,507	532,714
Scores | Operating Segments
Segment revenues:
Total revenues	474,973	297,039	779,507	532,714
Segment operating expense	(42,497)	(32,069)	(79,178)	(63,973)
Operating income	432,476	264,970	700,329	468,741
Software
Segment revenues:
Total revenues	216,704	201,696	424,129	405,989
Software | Operating Segments
Segment revenues:
Total revenues	216,704	201,696	424,129	405,989
Segment operating expense	(154,110)	(138,372)	(302,921)	(281,923)
Operating income	62,594	63,324	121,208	124,066
On-premises and SaaS software
Segment revenues:
Total revenues	199,231	183,826	387,452	369,837
On-premises and SaaS software | Operating Segments
Segment revenues:
Total revenues			387,452	369,837
On-premises and SaaS software | Scores | Operating Segments
Segment revenues:
Total revenues	0	0	0	0
On-premises and SaaS software | Software
Segment revenues:
Total revenues	199,231	183,826	387,452	369,837
On-premises and SaaS software | Software | Operating Segments
Segment revenues:
Total revenues	199,231	183,826	387,452	369,837
Professional services
Segment revenues:
Total revenues	17,473	17,870	36,677	36,152
Professional services | Operating Segments
Segment revenues:
Total revenues			36,677	36,152
Professional services | Scores | Operating Segments
Segment revenues:
Total revenues	0	0	0	0
Professional services | Software | Operating Segments
Segment revenues:
Total revenues	17,473	17,870	36,677	36,152
Scores
Segment revenues:
Total revenues	474,973	297,039	779,507	532,714
Scores | Operating Segments
Segment revenues:
Total revenues			779,507	532,714
Scores | Scores | Operating Segments
Segment revenues:
Total revenues	474,973	297,039	779,507	532,714
Scores | Software | Operating Segments
Segment revenues:
Total revenues	$ 0	$ 0	$ 0	$ 0