Shares Used in Computing Net Income Per Share Attributable to Fiserv, Inc. - Schedule of Weighted-Average Number of Shares (Details) - shares shares in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2024 |
Jun. 30, 2023 |
Jun. 30, 2024 |
Jun. 30, 2023 |
|
| Earnings Per Share [Abstract] | ||||
| Weighted-average common shares outstanding used for the calculation of net income attributable to Fiserv, Inc. per share – basic (in shares) | 582.7 | 615.4 | 586.8 | 621.2 |
| Common stock equivalents (in shares) | 2.7 | 3.8 | 3.3 | 4.1 |
| Weighted-average common shares outstanding used for the calculation of net income attributable to Fiserv, Inc. per share – diluted (in shares) | 585.4 | 619.2 | 590.1 | 625.3 |