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Intangible Assets - Narrative (Details) $ in Millions | 12 Months Ended
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Dec. 31, 2020 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract] |
Accelerated amortization expense | $ 56

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- Definition Restructuring And Related Cost, Accelerated Amortization + References No definition available. + Details
Name: | fisv_RestructuringAndRelatedCostAcceleratedAmortization
Namespace Prefix: | fisv_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- References No definition available. + Details
Name: | us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration