Goodwill and Intangible Assets - Summary of Changes to Goodwill (Detail) $ in Thousands	6 Months Ended
	Mar. 31, 2017 USD ($)
Goodwill [Roll Forward]
Balance at September 30, 2016	$ 798,415
Foreign currency translation adjustment	(5,995)
Balance at March 31, 2017	792,420
Applications
Goodwill [Roll Forward]
Balance at September 30, 2016	582,720
Foreign currency translation adjustment	(5,538)
Balance at March 31, 2017	577,182
Scores
Goodwill [Roll Forward]
Balance at September 30, 2016	146,648
Foreign currency translation adjustment	0
Balance at March 31, 2017	146,648
Decision Management Software
Goodwill [Roll Forward]
Balance at September 30, 2016	69,047
Foreign currency translation adjustment	(457)
Balance at March 31, 2017	$ 68,590