Segment Information - Selected Financial Data, Revenues and Long lived Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 1,258,294	$ 1,009,780	$ 1,024,191
Long lived assets
Long-lived Assets	2,285,547	1,528,930
Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	510,300	275,526	271,421
Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	77,711	75,573	94,036
Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	102,897	95,403	83,173
Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	69,809	83,683	74,106
Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	100,609	94,261	72,872
Retail Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	396,968	385,334	428,583
Americas - United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	781,820	500,479	541,235
Long lived assets
Long-lived Assets	1,526,046	811,435
Americas - Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	77,370	71,546	82,231
EMEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	301,664	345,046	318,260
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	97,440	92,709	82,465
Other
Long lived assets
Long-lived Assets	759,501	717,495
Operating Segments | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	579,334	576,755	598,590
Operating Segments | ACI On Premise | Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	0	0	0
Operating Segments | ACI On Premise | Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	32,980	35,231	47,973
Operating Segments | ACI On Premise | Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	25,693	30,447	27,155
Operating Segments | ACI On Premise | Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	33,790	42,353	32,478
Operating Segments | ACI On Premise | Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	97,153	92,068	70,087
Operating Segments | ACI On Premise | Retail Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	389,718	376,656	420,897
Operating Segments | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	678,960	433,025	425,601
Operating Segments | ACI On Demand | Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	510,300	275,526	271,421
Operating Segments | ACI On Demand | Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	44,731	40,342	46,063
Operating Segments | ACI On Demand | Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	77,204	64,956	56,018
Operating Segments | ACI On Demand | Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	36,019	41,330	41,628
Operating Segments | ACI On Demand | Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	3,456	2,193	2,785
Operating Segments | ACI On Demand | Retail Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	7,250	8,678	7,686
Operating Segments | Americas - United States | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	172,660	131,382	175,682
Operating Segments | Americas - United States | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	609,160	369,097	365,553
Operating Segments | Americas - Other | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	68,020	61,969	72,802
Operating Segments | Americas - Other | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	9,350	9,577	9,429
Operating Segments | EMEA | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	251,035	296,157	270,388
Operating Segments | EMEA | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	50,629	48,889	47,872
Operating Segments | Asia Pacific | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	87,619	87,247	79,718
Operating Segments | Asia Pacific | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 9,821	$ 5,462	$ 2,747