Basis of Presentation (Policies)	6 Months Ended
Jun. 30, 2019
Accounting Policies [Abstract]
Principles of Consolidation, Policy	Principles of Consolidation The consolidated financial statements include the accounts of Fiserv, Inc. and all 100% owned subsidiaries. Investments in less than 50% owned affiliates in which the Company has significant influence but not control are accounted for using the equity method of accounting. All intercompany transactions and balances have been eliminated in consolidation.
Recently Adopted And Issued Accounting Pronouncements, Policy	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In June 2018, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), which simplifies the accounting for share-based payments granted to nonemployees by largely aligning it with the accounting for share-based payments to employees. For public entities, ASU 2018-07 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Entities must apply the standard, using a modified retrospective transition approach, with a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption for all liability-classified nonemployee awards that have not been settled as of the adoption date and equity-classified nonemployee awards for which a measurement date has not been established. The Company adopted ASU 2018-07 on January 1, 2019, and the adoption did not have any impact on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, which requires lessees to recognize a lease liability and a right-of-use asset for each lease with a term longer than twelve months. The recognized liability is measured at the present value of lease payments not yet paid, and the corresponding asset represents the lessee’s right to use the underlying asset over the lease term and is based on the liability, subject to certain adjustments. For income statement and statement of cash flow purposes, the standard retains the dual model with leases classified as either operating or finance. Operating leases result in straight-line expense while finance leases result in a front-loaded expense pattern. The standard prescribes a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. ASU 2016-02 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842; ASU No. 2018-11, Leases (Topic 842) - Targeted Improvements; ASU No. 2018-20, Narrow-Scope Improvements for Lessors; and ASU No. 2019-01, Leases (Topic 842) - Codification Improvements. ASU No. 2018-11 provides an additional transition method allowing entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. For public entities, ASU 2016-02 is effective for annual and interim periods beginning after December 15, 2018. The Company adopted the new standard effective January 1, 2019 using the optional transition method in ASU No. 2018-11. Under this method, the Company has not adjusted its comparative period financial statements for the effects of the new standard or made the new, expanded required disclosures for periods prior to the effective date. The Company elected the package of practical expedients permitted under the transition guidance in ASU 2016-02 to not reassess prior conclusions related to contracts containing leases, lease classification and initial direct costs. The Company also elected the practical expedient not to separate the non-lease components of a contract from the lease component to which they relate. The adoption of the new lease standard resulted in the recognition of lease liabilities of $383 million and right-of-use assets of $343 million, which include the impact of existing deferred rents and tenant improvement allowances on the consolidated balance sheet as of January 1, 2019 for real and personal property operating leases. The adoption of ASU 2016-02 did not have a material impact on the Company’s consolidated statements of income or consolidated statements of cash flows. Recently Issued Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”), which aligns the requirements for capitalizing implementation costs incurred in a cloud computing hosting arrangement that is a service contract with the requirements under Accounting Standards Codification (“ASC”) 350 for capitalizing implementation costs incurred to develop or obtain internal-use software. For public entities, ASU 2018-15 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019, with early adoption permitted. Entities are permitted to apply either a retrospective or prospective transition approach to adopt the guidance. The Company plans to adopt ASU 2018-15 on January 1, 2020 and does not expect the adoption to have a material impact on its consolidated financial statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which removes, modifies, and adds certain disclosure requirements of ASC Topic 820, Fair Value Measurement. ASU 2018-13 is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019, with the additional disclosures required to be applied prospectively and the modified and removed disclosures required to be applied retrospectively to all periods presented. Entities are permitted to early adopt the removed or modified disclosures and delay the adoption of the additional disclosures until the effective date. The Company is currently assessing the impact that the adoption of ASU 2018-13 will have on its consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) (“ASU 2016-13”), which prescribes an impairment model for most financial instruments based on expected losses rather than incurred losses. Under this model, an estimate of expected credit losses over the contractual life of the instrument is to be recorded as of the end of a reporting period as an allowance to offset the amortized cost basis, resulting in a net presentation of the amount expected to be collected on the financial instrument. For public entities, ASU 2016-13 is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. For most instruments, entities must apply the standard using a cumulative-effect adjustment to beginning retained earnings as of the beginning of the fiscal year of adoption. The Company is currently assessing the impact that the adoption of ASU 2016-13 will have on its consolidated financial statements.
Revenue from Contract with Customer, Policy	The Company applies the optional exemption in paragraph 606-10-50-14(b) and does not disclose information about remaining performance obligations for account- and transaction-based processing fees that qualify for recognition in accordance with paragraph 606-10-55-18. These contracts generally have terms of three to five years, and contain variable consideration for stand-ready performance obligations for which the exact quantity and mix of transactions to be processed are contingent upon the customer’s request. The Company also applies the optional exemptions in paragraph 606-10-50-14A and does not disclose information for variable consideration, including additional seat licenses, that is a sales-based or usage-based royalty promised in exchange for a license of intellectual property or that is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct good or service in a series. The amounts disclosed above as remaining performance obligations consist primarily of fixed or monthly minimum processing fees and maintenance fees under contracts with an original expected duration of greater than one year. Contract assets, reported within other long-term assets in the consolidated balance sheets, primarily result from revenue being recognized where payment is contingent upon the transfer of services to a customer over the contractual period. Contract liabilities primarily relate to advance consideration received from customers (deferred revenue) for which transfer of control occurs, and therefore revenue is recognized, as services are provided. Contract balances are reported in a net contract asset or liability position on a contract-by-contract basis at the end of each reporting period. The Company generates revenue from the delivery of processing, service and product solutions. Revenue is measured based on consideration specified in a contract with a customer, and excludes any amounts collected on behalf of third parties. The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer which may be at a point in time or over time.
Leases, Policy	The Company determines if an arrangement is a lease at inception. The lease term begins on the commencement date, which is the date the Company takes possession of the property, and may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. The lease term is used to determine lease classification as an operating or finance lease and is used to calculate straight-line lease expense for operating leases. The Company elected the package of practical expedients permitted under the transition guidance within ASU 2016-02 to not reassess prior conclusions related to contracts containing leases, lease classification and initial direct costs. Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. As a practical expedient, lease agreements with lease and non-lease components are accounted for as a single lease component for all asset classes, which are comprised of real estate leases and equipment leases. ROU assets and lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. ROU assets also include prepaid lease payments and exclude lease incentives received. The Company estimates contingent lease incentives when it is probable that the Company is entitled to the incentive at lease commencement. As the Company’s leases typically do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date for both real estate and equipment leases. The determination of the incremental borrowing rate requires judgment. The Company determines the incremental borrowing rate using the Company’s current unsecured borrowing rate, adjusted for various factors such as collateralization and term to align with the terms of the lease. The Company elected the short-term lease recognition exemption for all leases that qualify. Therefore, leases with an initial term of 12 months or less are not recorded on the balance sheet; instead, lease payments are recognized as lease expense on a straight-line basis over the lease term. The Company leases certain office space, data centers, and equipment. The Company’s leases have remaining lease terms of one to 11 years. Most leases contain renewal options for varying periods, which are at the Company’s sole discretion. For leases where the Company is reasonably certain to exercise a renewal option, such option periods have been included in the determination of the Company’s ROU assets and lease liabilities. Certain leases require the Company to pay taxes, insurance, maintenance, and other operating expenses associated with the leased asset. Such amounts are not included in the measurement of the lease liability to the extent they are variable in nature. These variable lease costs are recognized as a variable lease expense when incurred. Certain leases include options to purchase the leased asset at the end of the lease term, which is assessed as a part of the Company’s lease classification determination. The depreciable life of the ROU assets and leasehold improvements are limited by the expected lease term unless the Company is reasonably certain of a transfer of title or purchase option.

Basis of Presentation (Policies)

6 Months Ended

Jun. 30, 2019

Principles of Consolidation

The consolidated financial statements include the accounts of Fiserv, Inc. and all 100% owned subsidiaries. Investments in less than 50% owned affiliates in which the Company has significant influence but not control are accounted for using the equity method of accounting. All intercompany transactions and balances have been eliminated in consolidation.

Recently Adopted And Issued Accounting Pronouncements, Policy

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In June 2018, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2018-07, Compensation - Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”), which simplifies the accounting for share-based payments granted to nonemployees by largely aligning it with the accounting for share-based payments to employees. For public entities, ASU 2018-07 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018. Entities must apply the standard, using a modified retrospective transition approach, with a cumulative-effect adjustment to retained earnings as of the beginning of the fiscal year of adoption for all liability-classified nonemployee awards that have not been settled as of the adoption date and equity-classified nonemployee awards for which a measurement date has not been established. The Company adopted ASU 2018-07 on January 1, 2019, and the adoption did not have any impact on its consolidated financial statements.

In February 2016, the FASB issued ASU No. 2016-02, which requires lessees to recognize a lease liability and a right-of-use asset for each lease with a term longer than twelve months. The recognized liability is measured at the present value of lease payments not yet paid, and the corresponding asset represents the lessee’s right to use the underlying asset over the lease term and is based on the liability, subject to certain adjustments. For income statement and statement of cash flow purposes, the standard retains the dual model with leases classified as either operating or finance. Operating leases result in straight-line expense while finance leases result in a front-loaded expense pattern. The standard prescribes a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. ASU 2016-02 was subsequently amended by ASU No. 2018-01, Land Easement Practical Expedient for Transition to Topic 842; ASU No. 2018-10, Codification Improvements to Topic 842; ASU No. 2018-11, Leases (Topic 842) - Targeted Improvements; ASU No. 2018-20, Narrow-Scope Improvements for Lessors; and ASU No. 2019-01, Leases (Topic 842) - Codification Improvements. ASU No. 2018-11 provides an additional transition method allowing entities to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. For public entities, ASU 2016-02 is effective for annual and interim periods beginning after December 15, 2018.

The Company adopted the new standard effective January 1, 2019 using the optional transition method in ASU No. 2018-11. Under this method, the Company has not adjusted its comparative period financial statements for the effects of the new standard or made the new, expanded required disclosures for periods prior to the effective date. The Company elected the package of practical expedients permitted under the transition guidance in ASU 2016-02 to not reassess prior conclusions related to contracts containing leases, lease classification and initial direct costs. The Company also elected the practical expedient not to separate the non-lease components of a contract from the lease component to which they relate.

The adoption of the new lease standard resulted in the recognition of lease liabilities of $383 million and right-of-use assets of $343 million, which include the impact of existing deferred rents and tenant improvement allowances on the consolidated balance sheet as of January 1, 2019 for real and personal property operating leases. The adoption of ASU 2016-02 did not have a material impact on the Company’s consolidated statements of income or consolidated statements of cash flows.

Recently Issued Accounting Pronouncements

In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”), which aligns the requirements for capitalizing implementation costs incurred in a cloud computing hosting arrangement that is a service contract with the requirements under Accounting Standards Codification (“ASC”) 350 for capitalizing implementation costs incurred to develop or obtain internal-use software. For public entities, ASU 2018-15 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019, with early adoption permitted. Entities are permitted to apply either a retrospective or prospective transition approach to adopt the guidance. The Company plans to adopt ASU 2018-15 on January 1, 2020 and does not expect the adoption to have a material impact on its consolidated financial statements.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (“ASU 2018-13”), which removes, modifies, and adds certain disclosure requirements of ASC Topic 820, Fair Value Measurement. ASU 2018-13 is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019, with the additional disclosures required to be applied prospectively and the modified and removed disclosures required to be applied retrospectively to all periods presented. Entities are permitted to early adopt the removed or modified disclosures and delay the adoption of the additional disclosures until the effective date. The Company is currently assessing the impact that the adoption of ASU 2018-13 will have on its consolidated financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326) (“ASU 2016-13”), which prescribes an impairment model for most financial instruments based on expected losses rather than incurred losses. Under this model, an estimate of expected credit losses over the contractual life of the instrument is to be recorded as of the end of a reporting period as an allowance to offset the amortized cost basis, resulting in a net presentation of the amount expected to be collected on the financial instrument. For public entities, ASU 2016-13 is effective for fiscal years, including interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. For most instruments, entities must apply the standard using a cumulative-effect adjustment to beginning retained earnings as of the beginning of the fiscal year of adoption. The Company is currently assessing the impact that the adoption of ASU 2016-13 will have on its consolidated financial statements.

Revenue from Contract with Customer, Policy

The Company applies the optional exemption in paragraph 606-10-50-14(b) and does not disclose information about remaining performance obligations for account- and transaction-based processing fees that qualify for recognition in accordance with paragraph 606-10-55-18. These contracts generally have terms of three to five years, and contain variable consideration for stand-ready performance obligations for which the exact quantity and mix of transactions to be processed are contingent upon the customer’s request. The Company also applies the optional exemptions in paragraph 606-10-50-14A and does not disclose information for variable consideration, including additional seat licenses, that is a sales-based or usage-based royalty promised in exchange for a license of intellectual property or that is allocated entirely to a wholly unsatisfied performance obligation or to a wholly unsatisfied promise to transfer a distinct good or service in a series. The amounts disclosed above as remaining performance obligations consist primarily of fixed or monthly minimum processing fees and maintenance fees under contracts with an original expected duration of greater than one year.

Contract assets, reported within other long-term assets in the consolidated balance sheets, primarily result from revenue being recognized where payment is contingent upon the transfer of services to a customer over the contractual period. Contract liabilities primarily relate to advance consideration received from customers (deferred revenue) for which transfer of control occurs, and therefore revenue is recognized, as services are provided. Contract balances are reported in a net contract asset or liability position on a contract-by-contract basis at the end of each reporting period.

The Company generates revenue from the delivery of processing, service and product solutions. Revenue is measured based on consideration specified in a contract with a customer, and excludes any amounts collected on behalf of third parties. The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer which may be at a point in time or over time.

Leases, Policy

The Company determines if an arrangement is a lease at inception. The lease term begins on the commencement date, which is the date the Company takes possession of the property, and may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. The lease term is used to determine lease classification as an operating or finance lease and is used to calculate straight-line lease expense for operating leases. The Company elected the package of practical expedients permitted under the transition guidance within ASU 2016-02 to not reassess prior conclusions related to contracts containing leases, lease classification and initial direct costs.

Right-of-use (“ROU”) assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. As a practical expedient, lease agreements with lease and non-lease components are accounted for as a single lease component for all asset classes, which are comprised of real estate leases and equipment leases. ROU assets and lease liabilities are recognized at commencement date based on the present value of lease payments over the lease term. ROU assets also include prepaid lease payments and exclude lease incentives received. The Company estimates contingent lease incentives when it is probable that the Company is entitled to the incentive at lease commencement. As the Company’s leases typically do not provide an implicit rate, the Company uses its incremental borrowing rate based on the information available at commencement date for both real estate and equipment leases. The determination of the incremental borrowing rate requires judgment. The Company determines the incremental borrowing rate using the Company’s current unsecured borrowing rate, adjusted for various factors such as collateralization and term to align with the terms of the lease. The Company elected the short-term lease recognition exemption for all leases that qualify. Therefore, leases with an initial term of 12 months or less are not recorded on the balance sheet; instead, lease payments are recognized as lease expense on a straight-line basis over the lease term.

The Company leases certain office space, data centers, and equipment. The Company’s leases have remaining lease terms of one to 11 years. Most leases contain renewal options for varying periods, which are at the Company’s sole discretion. For leases where the Company is reasonably certain to exercise a renewal option, such option periods have been included in the determination of the Company’s ROU assets and lease liabilities. Certain leases require the Company to pay taxes, insurance, maintenance, and other operating expenses associated with the leased asset. Such amounts are not included in the measurement of the lease liability to the extent they are variable in nature. These variable lease costs are recognized as a variable lease expense when incurred. Certain leases include options to purchase the leased asset at the end of the lease term, which is assessed as a part of the Company’s lease classification determination. The depreciable life of the ROU assets and leasehold improvements are limited by the expected lease term unless the Company is reasonably certain of a transfer of title or purchase option.