Condensed Consolidated Financial Statements - Summary of Changes in the Carrying Amount of Goodwill (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill, gross amount prior to beginning of period		$ 1,327,957
Goodwill, total impairment prior to beginning of period		(47,432)
Goodwill [Roll Forward]
Goodwill, beginning of period	$ 1,280,525
Goodwill from acquisitions	(299)
Goodwill, end of period	1,280,226
ACI On Demand
Goodwill [Line Items]
Goodwill, gross amount prior to beginning of period		554,617
Goodwill, total impairment prior to beginning of period		0
Goodwill [Roll Forward]
Goodwill, beginning of period	554,617
Goodwill from acquisitions	(299)
Goodwill, end of period	554,318
ACI On Premise
Goodwill [Line Items]
Goodwill, gross amount prior to beginning of period		773,340
Goodwill, total impairment prior to beginning of period		$ (47,432)
Goodwill [Roll Forward]
Goodwill, beginning of period	725,908
Goodwill from acquisitions	0
Goodwill, end of period	$ 725,908