Segment Information - Selected Financial Data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Segment Reporting Information [Line Items]
Revenues	$ 316,914	$ 315,883	$ 903,769	$ 907,278
Depreciation and amortization	(33,380)	(35,490)	(100,366)	(105,004)
Stock-based compensation expense	(6,367)	(8,061)	(20,790)	(22,943)
Corporate and unallocated expenses	(46,066)	(49,762)	(133,593)	(142,127)
Interest, net	(8,374)	(9,998)	(25,390)	(35,457)
Other, net	(1,088)	1,356	(1,036)	(6,361)
Income before income taxes	18,517	22,540	20,667	7,219
Bill Payments
Segment Reporting Information [Line Items]
Revenues	146,181	149,464	446,974	440,543
Digital Business Banking
Segment Reporting Information [Line Items]
Revenues	16,527	14,443	47,319	45,327
Merchant Payments
Segment Reporting Information [Line Items]
Revenues	38,989	40,761	115,083	109,870
Fraud Management
Segment Reporting Information [Line Items]
Revenues	6,882	11,513	23,563	25,183
Real-Time Payments
Segment Reporting Information [Line Items]
Revenues	27,638	12,998	58,534	57,160
Issuing and Acquiring
Segment Reporting Information [Line Items]
Revenues	80,697	86,704	212,296	229,195
Banks
Segment Reporting Information [Line Items]
Revenues	131,744	125,658	341,712	356,865
Merchants
Segment Reporting Information [Line Items]
Revenues	38,989	40,761	115,083	109,870
Billers
Segment Reporting Information [Line Items]
Revenues	146,181	149,464	446,974	440,543
Operating Segments | Banks
Segment Reporting Information [Line Items]
Revenues	131,744	125,658	341,712	356,865
Segment Adjusted EBITDA	67,602	71,666	159,262	182,487
Operating Segments | Banks | Bill Payments
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Banks | Digital Business Banking
Segment Reporting Information [Line Items]
Revenues	16,527	14,443	47,319	45,327
Operating Segments | Banks | Merchant Payments
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Banks | Fraud Management
Segment Reporting Information [Line Items]
Revenues	6,882	11,513	23,563	25,183
Operating Segments | Banks | Real-Time Payments
Segment Reporting Information [Line Items]
Revenues	27,638	12,998	58,534	57,160
Operating Segments | Banks | Issuing and Acquiring
Segment Reporting Information [Line Items]
Revenues	80,697	86,704	212,296	229,195
Operating Segments | Merchants
Segment Reporting Information [Line Items]
Revenues	38,989	40,761	115,083	109,870
Segment Adjusted EBITDA	14,221	18,954	41,987	38,210
Operating Segments | Merchants | Bill Payments
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Merchants | Digital Business Banking
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Merchants | Merchant Payments
Segment Reporting Information [Line Items]
Revenues	38,989	40,761	115,083	109,870
Operating Segments | Merchants | Fraud Management
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Merchants | Real-Time Payments
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Merchants | Issuing and Acquiring
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Billers
Segment Reporting Information [Line Items]
Revenues	146,181	149,464	446,974	440,543
Segment Adjusted EBITDA	31,969	33,875	100,593	98,414
Operating Segments | Billers | Bill Payments
Segment Reporting Information [Line Items]
Revenues	146,181	149,464	446,974	440,543
Operating Segments | Billers | Digital Business Banking
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Billers | Merchant Payments
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Billers | Fraud Management
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Billers | Real-Time Payments
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Billers | Issuing and Acquiring
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0