Revenue from Contracts with Customers Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 314,249	$ 254,993	$ 854,739	$ 743,614
Applications
Disaggregation of Revenue [Line Items]
Revenues	165,637	138,658	455,111	425,328
Scores
Disaggregation of Revenue [Line Items]
Revenues	115,146	90,829	305,232	246,363
Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	33,466	25,506	94,396	71,923
North America
Disaggregation of Revenue [Line Items]
Revenues	213,868	182,914	595,031	530,301
North America | Applications
Disaggregation of Revenue [Line Items]
Revenues	88,210	80,598	256,385	250,700
North America | Scores
Disaggregation of Revenue [Line Items]
Revenues	110,728	89,261	293,292	240,703
North America | Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	14,930	13,055	45,354	38,898
Latin America
Disaggregation of Revenue [Line Items]
Revenues	13,304	6,871	48,661	22,594
Latin America | Applications
Disaggregation of Revenue [Line Items]
Revenues	7,088	5,364	32,011	17,531
Latin America | Scores
Disaggregation of Revenue [Line Items]
Revenues	768	399	2,650	1,484
Latin America | Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	5,448	1,108	14,000	3,579
Europe, Middle East and Africa
Disaggregation of Revenue [Line Items]
Revenues	65,042	40,209	147,145	126,517
Europe, Middle East and Africa | Applications
Disaggregation of Revenue [Line Items]
Revenues	54,171	34,374	119,971	107,686
Europe, Middle East and Africa | Scores
Disaggregation of Revenue [Line Items]
Revenues	2,191	691	5,197	2,446
Europe, Middle East and Africa | Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	8,680	5,144	21,977	16,385
Asia Pacific
Disaggregation of Revenue [Line Items]
Revenues	22,035	24,999	63,902	64,202
Asia Pacific | Applications
Disaggregation of Revenue [Line Items]
Revenues	16,168	18,322	46,744	49,411
Asia Pacific | Scores
Disaggregation of Revenue [Line Items]
Revenues	1,459	478	4,093	1,730
Asia Pacific | Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	4,408	6,199	13,065	13,061
On-Premises [Member]
Disaggregation of Revenue [Line Items]
Revenues	129,811	106,100	350,051	319,851
On-Premises [Member] | Applications
Disaggregation of Revenue [Line Items]
Revenues	102,673	83,904	273,579	256,557
On-Premises [Member] | Scores
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
On-Premises [Member] | Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	27,138	22,196	76,472	63,294
SaaS Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	69,292	58,064	199,456	177,400
SaaS Products [Member] | Applications
Disaggregation of Revenue [Line Items]
Revenues	62,964	54,754	181,532	168,771
SaaS Products [Member] | Scores
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
SaaS Products [Member] | Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	6,328	3,310	17,924	8,629
Scores Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	115,146	90,829	305,232	246,363
Scores Products [Member] | Applications
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Scores Products [Member] | Scores
Disaggregation of Revenue [Line Items]
Revenues	115,146	90,829	305,232	246,363
Scores Products [Member] | Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0