Segment Information - Selected Financial Data, Revenues and Long lived Assets (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 1,294,322	$ 1,258,294	$ 1,009,780
Long lived assets
Long-lived Assets	2,174,513	2,285,547
Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	586,047	510,300	275,526
Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	75,707	77,711	75,573
Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	108,727	102,897	95,403
Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	62,065	69,809	83,683
Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	81,060	100,609	94,261
Issuing and Acquiring
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	380,716	396,968	385,334
Americas - United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	830,511	781,820	500,479
Long lived assets
Long-lived Assets	1,423,862	1,526,046
Americas - Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	73,094	77,370	71,546
EMEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	293,226	301,664	345,046
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	97,491	97,440	92,709
Other
Long lived assets
Long-lived Assets	750,651	759,501
Operating Segments \| ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	769,180	678,960	433,025
Operating Segments \| ACI On Demand \| Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	586,047	510,300	275,526
Operating Segments \| ACI On Demand \| Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	46,269	44,731	40,342
Operating Segments \| ACI On Demand \| Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	84,997	77,204	64,956
Operating Segments \| ACI On Demand \| Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	40,495	36,019	41,330
Operating Segments \| ACI On Demand \| Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	3,902	3,456	2,193
Operating Segments \| ACI On Demand \| Issuing and Acquiring
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	7,470	7,250	8,678
Operating Segments \| ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	525,142	579,334	576,755
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	29,438	32,980	35,231
Operating Segments \| ACI On Premise \| Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	23,730	25,693	30,447
Operating Segments \| ACI On Premise \| Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	21,570	33,790	42,353
Operating Segments \| ACI On Premise \| Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	77,158	97,153	92,068
Operating Segments \| ACI On Premise \| Issuing and Acquiring
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	373,246	389,718	376,656
Operating Segments \| Americas - United States \| ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	687,923	609,160	369,097
Operating Segments \| Americas - United States \| ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	142,588	172,660	131,382
Operating Segments \| Americas - Other \| ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	11,561	9,350	9,577
Operating Segments \| Americas - Other \| ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	61,533	68,020	61,969
Operating Segments \| EMEA \| ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	58,857	50,629	48,889
Operating Segments \| EMEA \| ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	234,369	251,035	296,157
Operating Segments \| Asia Pacific \| ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	10,839	9,821	5,462
Operating Segments \| Asia Pacific \| ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 86,652	$ 87,619	$ 87,247