SEGMENT INFORMATION - Summary (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) reporting_units	Jun. 30, 2019 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | reporting_units			3
Segment Reporting Information [Line Items]
Revenues	$ 1,671,952	$ 935,152	$ 3,575,550	$ 1,818,190
Operating income (loss)	107,574	221,726	351,553	421,218
Depreciation and amortization	402,675	145,123	800,493	293,753
Intersegment Eliminations
Segment Reporting Information [Line Items]
Revenues	(16,350)	0	(35,729)	0
Corporate
Segment Reporting Information [Line Items]
Operating income (loss)	(173,726)	(65,281)	(324,316)	(107,357)
Depreciation and amortization	5,467	1,045	9,885	2,108
Acquisition-related costs	80,700	10,500	150,400	11,100
Merchant Solutions | Operating segments
Segment Reporting Information [Line Items]
Revenues	1,001,555	929,914	2,216,824	1,807,696
Operating income (loss)	175,078	283,411	479,231	521,540
Depreciation and amortization	236,840	143,914	469,862	291,299
Acquisition-related costs	4,400	3,700	6,600	8,400
Issuer Solutions | Operating segments
Segment Reporting Information [Line Items]
Revenues	470,025	5,238	973,787	10,494
Operating income (loss)	58,027	3,596	117,331	7,035
Depreciation and amortization	136,254	164	272,991	346
Business and Consumer Solutions | Operating segments
Segment Reporting Information [Line Items]
Revenues	216,722	0	420,668	0
Operating income (loss)	48,195	0	79,307	0
Depreciation and amortization	$ 24,114	$ 0	$ 47,755	$ 0