Segment Information - Selected Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 299,910	$ 297,618	$ 591,395	$ 503,473
Depreciation and amortization	(35,692)	(29,778)	(69,514)	(54,630)
Stock-based compensation expense	(7,932)	(14,372)	(14,882)	(20,957)
Corporate and unallocated expenses	(19,402)	(36,141)	(43,943)	(60,803)
Interest, net	(11,188)	(12,326)	(25,459)	(20,907)
Other, net	2,041	1,402	(7,717)	(510)
Income (loss) before income taxes	19,991	(16,806)	(15,321)	(55,392)
Operating Segments | ACI On Demand
Segment Reporting Information [Line Items]
Revenue	180,573	172,499	373,523	282,347
Segment Adjusted EBITDA	33,071	17,340	56,192	17,078
Depreciation and amortization	(10,852)	(8,489)	(20,184)	(16,051)
Stock-based compensation expense	(2,273)	(2,214)	(4,299)	(4,165)
Operating Segments | ACI On Premise
Segment Reporting Information [Line Items]
Revenue	119,337	125,119	217,872	221,126
Segment Adjusted EBITDA	59,093	57,069	90,002	85,337
Depreciation and amortization	(3,431)	(3,019)	(6,537)	(6,049)
Stock-based compensation expense	(2,279)	(2,051)	(4,309)	(4,007)
Corporate and Other
Segment Reporting Information [Line Items]
Depreciation and amortization	(21,409)	(18,270)	(42,793)	(32,530)
Stock-based compensation expense	$ (3,380)	$ (10,107)	$ (6,274)	$ (12,785)