Goodwill and Intangible Assets - Summary of Changes to Goodwill (Detail) $ in Thousands	3 Months Ended
	Dec. 31, 2018 USD ($)
Goodwill [Roll Forward]
Balance at September 30, 2018	$ 800,890
Addition from acquisitions	980
Foreign currency translation adjustment	(3,077)
Balance at December 31, 2018	798,793
Applications
Goodwill [Roll Forward]
Balance at September 30, 2018	585,161
Addition from acquisitions	980
Foreign currency translation adjustment	(2,820)
Balance at December 31, 2018	583,321
Scores
Goodwill [Roll Forward]
Balance at September 30, 2018	146,648
Addition from acquisitions	0
Foreign currency translation adjustment	0
Balance at December 31, 2018	146,648
Decision Management Software
Goodwill [Roll Forward]
Balance at September 30, 2018	69,081
Addition from acquisitions	0
Foreign currency translation adjustment	(257)
Balance at December 31, 2018	$ 68,824