Segment Information - Disaggregation of revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 331,361	$ 307,971	$ 643,775	$ 606,475
North America [Member]
Disaggregation of Revenue [Line Items]
Revenues	246,678	223,156	482,972	434,406
Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenues	14,781	18,208	27,224	32,342
EMEA [Member]
Disaggregation of Revenue [Line Items]
Revenues	49,675	42,911	95,223	91,498
Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Revenues	20,227	23,696	38,356	48,229
On-Premises Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	88,469	105,188	182,467	214,845
SaaS Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	74,173	73,635	147,938	147,344
Scores Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	168,719	129,148	313,370	244,286
Scores
Disaggregation of Revenue [Line Items]
Revenues	168,719	129,148	313,370	244,286
Scores | North America [Member]
Disaggregation of Revenue [Line Items]
Revenues	159,047	123,249	299,457	233,446
Scores | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,740	2,619	3,043	2,903
Scores | EMEA [Member]
Disaggregation of Revenue [Line Items]
Revenues	5,642	1,720	7,355	3,258
Scores | Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Revenues	1,290	1,560	3,515	4,679
Scores | On-Premises Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Scores | SaaS Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Scores | Scores Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	168,719	129,148	313,370	244,286
Decision Management Software
Disaggregation of Revenue [Line Items]
Revenues	33,128	38,544	65,530	69,732
Decision Management Software | North America [Member]
Disaggregation of Revenue [Line Items]
Revenues	17,514	21,007	34,061	36,594
Decision Management Software | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenues	2,929	5,917	5,842	10,250
Decision Management Software | EMEA [Member]
Disaggregation of Revenue [Line Items]
Revenues	9,120	6,920	17,698	14,185
Decision Management Software | Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Revenues	3,565	4,700	7,929	8,703
Decision Management Software | On-Premises Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	22,287	28,847	45,065	52,526
Decision Management Software | SaaS Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	10,841	9,697	20,465	17,206
Decision Management Software | Scores Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	0	0	0	0
Applications
Disaggregation of Revenue [Line Items]
Revenues	129,514	140,279	264,875	292,457
Applications | North America [Member]
Disaggregation of Revenue [Line Items]
Revenues	70,117	78,900	149,454	164,366
Applications | Latin America [Member]
Disaggregation of Revenue [Line Items]
Revenues	9,112	9,672	18,339	19,189
Applications | EMEA [Member]
Disaggregation of Revenue [Line Items]
Revenues	34,913	34,271	70,170	74,055
Applications | Asia Pacific [Member]
Disaggregation of Revenue [Line Items]
Revenues	15,372	17,436	26,912	34,847
Applications | On-Premises Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	66,182	76,341	137,402	162,319
Applications | SaaS Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	63,332	63,938	127,473	130,138
Applications | Scores Products [Member]
Disaggregation of Revenue [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0
Revenue from Contract with Customer Benchmark [Member]
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	100.00%	100.00%	100.00%	100.00%
Revenue from Contract with Customer Benchmark [Member] | Scores
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	51.00%	42.00%	49.00%	40.00%
Revenue from Contract with Customer Benchmark [Member] | Decision Management Software
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	10.00%	12.00%	10.00%	12.00%
Revenue from Contract with Customer Benchmark [Member] | Applications
Disaggregation of Revenue [Line Items]
Concentration Risk, Percentage	39.00%	46.00%	41.00%	48.00%