Financial Instruments	9 Months Ended
Financial Instruments	Sep. 30, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial Instruments	Financial Instruments Fair Value Hedges The Company holds interest rate swaps with aggregate notional amounts of $1,854 million, £925 million and €500 million at September 30, 2021, and $1,000 million and €500 million at December 31, 2020, converting the interest rate exposure on certain of the Company's Senior USD Notes, Senior GBP Notes and Senior Euro Notes, as applicable, from fixed to variable. These swaps are designated as fair value hedges for accounting purposes with a net liability fair value of $77 million reflected as a decrease in the long-term debt balance at September 30, 2021, and a net asset fair value of $10 million reflected as an increase in the long-term debt balance at December 31, 2020 (see Note 5). Net Investment Hedges The purpose of the Company's net investment hedges, as discussed below, is to reduce the volatility of FIS' net investment value in its Euro- and Pound Sterling-denominated operations due to changes in foreign currency exchange rates. The Company recorded net investment hedge aggregate gain (loss) for the change in fair value as Foreign currency translation adjustments and related income tax (expense) benefit within Other comprehensive earnings (loss), net of tax, on the consolidated statements of comprehensive earnings (loss) of $386 million and $(597) million during the three months and $678 million and $(263) million during the nine months ended September 30, 2021 and 2020, respectively. No ineffectiveness has been recorded on the net investment hedges. Foreign Currency-Denominated Debt Designations The Company designates certain foreign currency-denominated debt as net investment hedges of its investment in Euro- and Pound Sterling-denominated operations. As of September 30, 2021, and December 31, 2020, an aggregate €7,127 million and €7,466 million, respectively, was designated as a net investment hedge of the Company's investment in Euro-denominated operations related to Senior Euro Notes with maturities ranging from 2022 to 2039 and ECP Notes. As of December 31, 2020, an additional €1,000 million was designated as a net investment hedge of the Company's investment in Euro-denominated operations related to the Senior Euro Floating Rate Notes and Senior Euro Notes with a 2021 maturity. As of September 30, 2021, and December 31, 2020, an aggregate £1,193 million and £1,850 million, respectively, was designated as a net investment hedge of the Company's Pound Sterling-denominated operations related to the Senior GBP Notes with maturities ranging from 2022 to 2031. Cross-Currency Interest Rate Swap Designations The Company holds cross-currency interest rate swaps and designates them as net investment hedges of its investment in Euro- and Pound Sterling-denominated operations. As of September 30, 2021, and December 31, 2020, aggregate notional amounts of €5,906 million and €4,508 million, respectively, were designated as net investment hedges of the Company's investment in Euro-denominated operations, and aggregate notional amounts of £2,345 million and £565 million, respectively, were designated as net investment hedges of the Company's Pound Sterling-denominated operations. The cross-currency interest rate swap fair values were net assets of $120 million and net liabilities of $306 million at September 30, 2021, and December 31, 2020, respectively.