Acquisitions and Dispositions - Narrative (Details) - USD ($) $ in Millions											3 Months Ended		12 Months Ended
	Nov. 01, 2023	Jul. 25, 2023	Dec. 20, 2022	Oct. 17, 2022	Sep. 30, 2022	Apr. 01, 2022	Nov. 22, 2021	Jun. 14, 2021	May 04, 2021	Jan. 22, 2021	Sep. 01, 2022	Jun. 14, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jun. 30, 2023
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired													$ 13	$ 988	$ 848
Goodwill													37,205	36,811	36,433
Tax expense													754	551	363
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Korea Operations
Business Acquisition [Line Items]
Consideration from sale of business					$ 50
Net proceeds from sale of businesses and other assets					43
Part noncash divestiture, amount of consideration received					7
Gain (loss) on disposition of business					(127)
Disposal group, including discontinued operation, goodwill					40
Disposal group, including discontinued operation, intangible assets					48
Disposal group, including discontinued operation, accumulated foreign currency translation loss					$ 56
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Fiserv Costa Rica, S.A.
Business Acquisition [Line Items]
Consideration from sale of business				$ 49
Gain (loss) on disposition of business				44									3
Tax expense				$ 8
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Financial Reconciliation Business
Business Acquisition [Line Items]
Net proceeds from sale of businesses and other assets		$ 235
Gain (loss) on disposition of business													172
Tax expense													48
Disposal group, including discontinued operation, goodwill													38
Disposal group, including discontinued operation, trade receivable and capitalized software													15
Disposal group, including discontinued operation, accumulated foreign currency translation loss													10
Merchant One, Inc.
Business Acquisition [Line Items]
Payments to acquire businesses, net of cash acquired			$ 302
Acquired cash			1
Measurement period adjustment, increase (decrease) in goodwill													$ 61
Intangible assets			$ 118													$ 118
Goodwill																179
Other net assets																$ 6
Weighted-average useful life (in years)			9 years
Finxact, Inc.
Business Acquisition [Line Items]
Acquired cash						$ 27
Intangible assets						105
Goodwill						670
Other net assets						1
Payments for acquisitions of businesses						$ 645
Pre-tax gain from remeasurement														110
Weighted-average useful life (in years)						6 years
BentoBox
Business Acquisition [Line Items]
Acquired cash							$ 24
Measurement period adjustment, increase (decrease) in goodwill														62
Intangible assets							52
Goodwill							266
Other net assets							23
Cash purchase price							$ 317
Measurement period adjustment, intangible assets														(84)
Measurement period adjustment, recognized deferred tax liabilities														$ 22
Weighted-average useful life (in years)							5 years
Pineapple Payments
Business Acquisition [Line Items]
Acquired cash									$ 6
Intangible assets									127
Goodwill									79
Other net assets									7
Payments for acquisitions of businesses									207
Earn-out provisions estimated fair value									30
Goodwill, expected tax deductible amount									$ 59
Weighted-average useful life (in years)									14 years
Ondot
Business Acquisition [Line Items]
Acquired cash										$ 13
Intangible assets										142
Goodwill										173
Payments for acquisitions of businesses										$ 271
Pre-tax gain from remeasurement															$ 12
Weighted-average useful life (in years)										6 years
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Intangible assets											$ 23
Goodwill											22
Payments for acquisitions of businesses											44
Earn-out provisions estimated fair value											6
Goodwill, expected tax deductible amount											$ 17
Weighted-average useful life (in years)											9 years
Other net assumed liabilities											$ 1
SpendLabs and Radius8
Business Acquisition [Line Items]
Intangible assets								$ 47				$ 47
Goodwill								61				61
Payments for acquisitions of businesses												87
Earn-out provisions estimated fair value												4
Goodwill, expected tax deductible amount								$ 14				14
Weighted-average useful life (in years)								7 years
Net assumed liabilities								$ 7				$ 7
Skytef and Sled
Business Acquisition [Line Items]
Payments for acquisitions of businesses	$ 17