Segment Information - Selected Financial Data, Revenues and Long lived Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 299,910	$ 297,618	$ 591,395	$ 503,473
Long-lived assets
Long-lived assets	2,225,869		2,225,869		$ 2,285,547
Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	137,122	125,339	290,808	194,306
Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	15,099	27,455	31,055	45,968
Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	27,009	25,579	50,129	49,940
Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	15,794	15,378	28,920	31,396
Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	25,956	22,716	44,252	38,049
Retail Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	78,930	81,151	146,231	143,814
Americas - United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	207,381	191,521	412,174	310,979
Long-lived assets
Long-lived assets	1,494,545		1,494,545		1,526,046
Americas - Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	3,669	14,520	24,843	28,208
EMEA
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	70,950	64,647	110,823	119,166
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	17,910	26,930	43,555	45,120
Other
Long-lived assets
Long-lived assets	731,324		731,324		$ 759,501
Operating Segments | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	180,573	172,499	373,523	282,347
Operating Segments | ACI On Demand | Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	137,122	125,339	290,808	194,306
Operating Segments | ACI On Demand | Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	7,328	18,011	15,721	27,799
Operating Segments | ACI On Demand | Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	21,413	17,942	40,427	37,281
Operating Segments | ACI On Demand | Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	11,852	8,874	20,865	17,855
Operating Segments | ACI On Demand | Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,004	907	2,001	1,525
Operating Segments | ACI On Demand | Retail Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,854	1,426	3,701	3,581
Operating Segments | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	119,337	125,119	217,872	221,126
Operating Segments | ACI On Premise | Bill Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	0	0	0	0
Operating Segments | ACI On Premise | Digital Channels
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	7,771	9,444	15,334	18,169
Operating Segments | ACI On Premise | Merchant Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	5,596	7,637	9,702	12,659
Operating Segments | ACI On Premise | Payments Intelligence
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	3,942	6,504	8,055	13,541
Operating Segments | ACI On Premise | Real-Time Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	24,952	21,809	42,251	36,524
Operating Segments | ACI On Premise | Retail Payments
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	77,076	79,725	142,530	140,233
Operating Segments | Americas - United States | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	158,720	155,825	334,374	248,861
Operating Segments | Americas - United States | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	48,661	35,696	77,800	62,118
Operating Segments | Americas - Other | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	2,419	2,107	5,652	4,850
Operating Segments | Americas - Other | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	1,250	12,413	19,191	23,358
Operating Segments | EMEA | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	16,524	12,492	27,442	24,560
Operating Segments | EMEA | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	54,426	52,155	83,381	94,606
Operating Segments | Asia Pacific | ACI On Demand
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	2,910	2,075	6,055	4,076
Operating Segments | Asia Pacific | ACI On Premise
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 15,000	$ 24,855	$ 37,500	$ 41,044