ACQUISITIONS - Narrative (Details) $ in Thousands		3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)
Business Acquisition [Line Items]
Goodwill acquired			$ 23,000
TSYS
Business Acquisition [Line Items]
Adjustment to goodwill			(39,684)
Goodwill acquired			17,400,000
Revenue of acquiree		$ 1,067,200	3,119,200
Operating income (loss) of acquiree		165,800	385,100
Employee termination benefits obligation	$ 26,300	26,300	26,300
Employee termination benefits charges	106,900	8,100	49,800
Employee termination benefits charges related to stock-based compensation	$ 23,400	$ 1,900	6,100
Merchant Solutions
Business Acquisition [Line Items]
Goodwill acquired			23,000
Merchant Solutions | TSYS
Business Acquisition [Line Items]
Goodwill acquired			7,100,000
Issuer Solutions
Business Acquisition [Line Items]
Goodwill acquired			0
Issuer Solutions | TSYS
Business Acquisition [Line Items]
Goodwill acquired			7,900,000
Business and Consumer Solutions
Business Acquisition [Line Items]
Goodwill acquired			0
Business and Consumer Solutions | TSYS
Business Acquisition [Line Items]
Goodwill acquired			$ 2,400,000