Goodwill and Intangible Assets - Summary of Changes to Goodwill (Detail) $ in Thousands	9 Months Ended
	Jun. 30, 2020 USD ($)
Goodwill [Roll Forward]
Balance at September 30, 2019	$ 803,542
Foreign currency translation adjustment	986
Balance at June 30, 2020	804,528
Applications
Goodwill [Roll Forward]
Balance at September 30, 2019	588,614
Foreign currency translation adjustment	986
Balance at June 30, 2020	589,600
Scores
Goodwill [Roll Forward]
Balance at September 30, 2019	146,648
Foreign currency translation adjustment	0
Balance at June 30, 2020	146,648
Decision Management Software
Goodwill [Roll Forward]
Balance at September 30, 2019	68,280
Foreign currency translation adjustment	0
Balance at June 30, 2020	$ 68,280