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Financial Instruments - (Narratives) (Details)	1 Months Ended	3 Months Ended			6 Months Ended
Financial Instruments - (Narratives) (Details)	May 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jul. 31, 2019 USD ($)	Jun. 30, 2019 EUR (€)	Jun. 30, 2019 GBP (£)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 EUR (€)	Sep. 30, 2017 EUR (€)	Sep. 30, 2017 GBP (£)
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Foreign currency transaction loss			$ 15,000,000
Notional amount										$ 0
Cash Flow Hedging
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Notional amount			0		$ 0					0
Euro Commercial Paper Program \| FIS Credit Agreements
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Commercial paper \| €								€ 1,500,000,000
Euro Commercial Paper Program \| Commercial paper \| FIS Credit Agreements
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Commercial paper			1,500,000,000		1,500,000,000
Euro Commercial Paper Program \| Commercial paper \| FIS Credit Agreements \| Subsequent Event
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Commercial paper							$ 2,900,000,000
Senior Euro Notes due July 2024, interest payable annually at 1.100% (2024 Euro Notes) \| Senior notes
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Principal amount of debt \| €												€ 500,000,000
Senior Euro Notes due January 2021, interest payable annually at 0.400% (2021 Euro Notes) \| Senior notes
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Principal amount of debt \| €												€ 500,000,000
Senior GBP Notes due June 2022, interest payable annually at 1.700% (2022 GBP Notes) \| Senior notes
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Principal amount of debt \| £													£ 300,000,000
Currency forward contract
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative liability fair value			14,000,000		14,000,000
Currency forward contract \| Net Investment Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Amount of gains reclassified from AOCE into income			6,000,000	$ 67,000,000	13,000,000	$ 28,000,000
Currency forward contract \| Subsequent Event
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Gain from settlement of derivative contract		$ 1,000,000
Interest rate swap \| Cash Flow Hedging
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Notional amount			500,000,000		500,000,000			€ 1,500,000,000	£ 500,000,000
Payments for the settlement of derivatives classified as hedging	$ 17,000,000
Interest rate swap \| Fair Value Hedging
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Notional amount \| €											€ 500,000,000
Interest rate swap \| Net Investment Hedges
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Notional amount										$ 716,000,000
Derivative asset fair value			10,000,000		10,000,000
Interest rate swap \| Senior Euro Notes due July 2024, interest payable annually at 1.100% (2024 Euro Notes) \| Fair Value Hedging \| Senior notes
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Derivative asset fair value			$ 14,000,000		$ 14,000,000