SEGMENT INFORMATION - Summary (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) reporting_units	Mar. 31, 2019 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | reporting_units	3
Segment Reporting Information [Line Items]
Revenues	$ 1,903,598	$ 883,039
Operating income (loss)	243,979	199,492
Depreciation and amortization	397,818	148,630
Operating segments
Segment Reporting Information [Line Items]
Revenues	1,922,977	883,039
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(19,379)	0
Corporate
Segment Reporting Information [Line Items]
Operating income (loss)	(150,590)	(42,076)
Depreciation and amortization	4,419	1,063
Acquisition-related costs	69,700	5,300
Merchant Solutions | Operating segments
Segment Reporting Information [Line Items]
Revenues	1,215,269	877,783
Operating income (loss)	304,153	238,129
Depreciation and amortization	233,021	147,385
Acquisition-related costs		2,200
Issuer Solutions | Operating segments
Segment Reporting Information [Line Items]
Revenues	503,762	5,256
Operating income (loss)	59,304	3,439
Depreciation and amortization	136,737	182
Business and Consumer Solutions | Operating segments
Segment Reporting Information [Line Items]
Revenues	203,946	0
Operating income (loss)	31,112	0
Depreciation and amortization	$ 23,641	$ 0