Goodwill and Intangible Assets - Summary of Changes to Goodwill (Detail) $ in Thousands	9 Months Ended
	Jun. 30, 2018 USD ($)
Goodwill [Roll Forward]
Balance at September 30, 2017	$ 804,414
Foreign currency translation adjustment	(2,373)
Balance at June 30, 2018	802,041
Applications
Goodwill [Roll Forward]
Balance at September 30, 2017	588,288
Foreign currency translation adjustment	(2,195)
Balance at June 30, 2018	586,093
Scores
Goodwill [Roll Forward]
Balance at September 30, 2017	146,648
Foreign currency translation adjustment	0
Balance at June 30, 2018	146,648
Decision Management Software
Goodwill [Roll Forward]
Balance at September 30, 2017	69,478
Foreign currency translation adjustment	(178)
Balance at June 30, 2018	$ 69,300