Segment Information - Summary of Segment Information (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Segment revenues:
Transactional and maintenance		$ 161,249	$ 150,743	$ 314,909	$ 297,815
Professional services		41,284	39,342	84,827	73,494
License		25,845	16,593	48,242	35,445
Total revenues		228,378	206,678	447,978	406,754
Segment operating expense		(188,337)	(168,154)	(373,010)	(337,396)
Operating income		40,041	38,524	74,968	69,358
Unallocated share-based compensation expense		(14,712)	(13,600)	(29,231)	(28,300)
Unallocated amortization expense	[1]	(3,312)	(3,507)	(6,632)	(7,087)
Unallocated interest expense		(6,578)	(6,815)	(12,750)	(13,539)
Unallocated other expense, net		(327)	435	(427)	101
Income before income taxes		33,136	32,144	61,791	55,920
Depreciation expense		5,738	4,220	11,347	8,081
Operating Segments
Segment revenues:
Segment operating expense		(170,313)	(151,047)	(337,147)	(302,009)
Operating income		58,065	55,631	110,831	104,745
Unallocated Corporate Expenses
Segment revenues:
Segment operating expense		(25,223)	(21,882)	(49,856)	(45,944)
Operating income		(25,223)	(21,882)	(49,856)	(45,944)
Depreciation expense		341	327	690	632
Applications | Operating Segments
Segment revenues:
Transactional and maintenance		86,013	80,751	170,894	161,734
Professional services		32,640	31,719	66,981	58,845
License		15,684	9,447	31,227	21,479
Total revenues		134,337	121,917	269,102	242,058
Segment operating expense		(99,454)	(87,955)	(199,251)	(175,392)
Operating income		34,883	33,962	69,851	66,666
Depreciation expense		3,959	2,708	7,827	5,452
Scores | Operating Segments
Segment revenues:
Transactional and maintenance		63,628	59,265	121,880	114,482
Professional services		994	1,112	1,515	1,860
License		811	739	1,420	776
Total revenues		65,433	61,116	124,815	117,118
Segment operating expense		(14,484)	(14,090)	(27,803)	(28,259)
Operating income		50,949	47,026	97,012	88,859
Depreciation expense		236	185	502	362
Decision Management Software | Operating Segments
Segment revenues:
Transactional and maintenance		11,608	10,727	22,135	21,599
Professional services		7,650	6,511	16,331	12,789
License		9,350	6,407	15,595	13,190
Total revenues		28,608	23,645	54,061	47,578
Segment operating expense		(31,152)	(27,120)	(60,237)	(52,414)
Operating income		(2,544)	(3,475)	(6,176)	(4,836)
Depreciation expense		$ 1,202	$ 1,000	$ 2,328	$ 1,635

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