Segment Information - Summary of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment revenues:
Transactional and maintenance		$ 195,491	$ 166,695	$ 565,348	$ 481,604
Professional services		43,209	43,871	131,913	128,698
License		20,805	20,420	55,423	68,662
Total revenues		259,505	230,986	752,684	678,964
Segment operating expense		(211,129)	(189,557)	(616,325)	(562,567)
Operating income		48,376	41,429	136,359	116,397
Unallocated share-based compensation expense		(18,883)	(14,315)	(54,631)	(43,546)
Unallocated amortization expense	[1]	(1,571)	(3,365)	(5,043)	(9,997)
Unallocated restructuring and acquisition-related		0	(4,471)	0	(4,471)
Unallocated interest expense		(8,223)	(6,653)	(21,799)	(19,403)
Unallocated other income, net		1,588	555	1,940	128
Income before income taxes		41,741	35,331	116,500	97,122
Depreciation expense		5,348	5,697	16,652	17,044
Operating Segments
Segment revenues:
Segment operating expense		(190,675)	(167,406)	(556,651)	(504,553)
Operating income		68,830	63,580	196,033	174,411
Unallocated Corporate Expenses
Segment revenues:
Segment operating expense		(31,922)	(26,724)	(92,175)	(76,580)
Operating income		(31,922)	(26,724)	(92,175)	(76,580)
Depreciation expense		215	331	737	1,021
Applications | Operating Segments
Segment revenues:
Transactional and maintenance		93,598	87,443	284,441	258,337
Professional services		34,173	35,990	107,542	102,971
License		13,847	10,349	37,743	41,576
Total revenues		141,618	133,782	429,726	402,884
Segment operating expense		(107,228)	(95,357)	(316,886)	(294,608)
Operating income		34,390	38,425	112,840	108,276
Depreciation expense		3,682	3,931	11,459	11,758
Scores | Operating Segments
Segment revenues:
Transactional and maintenance		90,716	68,376	245,934	190,256
Professional services		505	487	1,465	2,002
License		884	651	2,531	2,071
Total revenues		92,105	69,514	249,930	194,329
Segment operating expense		(16,374)	(14,013)	(48,673)	(41,816)
Operating income		75,731	55,501	201,257	152,513
Depreciation expense		130	239	432	741
Decision Management Software | Operating Segments
Segment revenues:
Transactional and maintenance		11,177	10,876	34,973	33,011
Professional services		8,531	7,394	22,906	23,725
License		6,074	9,420	15,149	25,015
Total revenues		25,782	27,690	73,028	81,751
Segment operating expense		(35,151)	(31,312)	(98,917)	(91,549)
Operating income		(9,369)	(3,622)	(25,889)	(9,798)
Depreciation expense		$ 1,321	$ 1,196	$ 4,024	$ 3,524

[1] Cost of revenues and selling, general and administrative expenses exclude the amortization of intangible assets. See Note 4.