Goodwill and Intangible Assets - Summary of Changes to Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Goodwill [Roll Forward]
Beginning Balance	$ 804,414	$ 798,415
Foreign currency translation adjustment	(3,524)	5,999
Ending Balance	800,890	804,414
Applications
Goodwill [Roll Forward]
Beginning Balance	588,288	582,720
Foreign currency translation adjustment	(3,127)	5,568
Ending Balance	585,161	588,288
Scores
Goodwill [Roll Forward]
Beginning Balance	146,648	146,648
Foreign currency translation adjustment	0	0
Ending Balance	146,648	146,648
Decision Management Software
Goodwill [Roll Forward]
Beginning Balance	69,478	69,047
Foreign currency translation adjustment	(397)	431
Ending Balance	$ 69,081	$ 69,478