Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue:
Total revenue		$ 19,093	$ 17,737	$ 16,226
Expenses:
Selling, general and administrative		6,576	6,059	5,810
Net gain on sale of businesses and other assets		(167)	(54)	0
Total expenses		14,079	13,997	13,938
Operating income		5,014	3,740	2,288
Interest expense, net		(976)	(733)	(693)
Other (expense) income, net		(140)	(94)	71
Income before income taxes and (loss) income from investments in unconsolidated affiliates		3,898	2,913	1,666
Income tax provision		(754)	(551)	(363)
(Loss) income from investments in unconsolidated affiliates		(15)	220	100
Net income		3,129	2,582	1,403
Less: net income attributable to noncontrolling interests and redeemable noncontrolling interests		61	52	69
Net income attributable to Fiserv, Inc.		$ 3,068	$ 2,530	$ 1,334
Net income attributable to Fiserv, Inc. per share:
Basic (in dollars per share)		$ 5.02	$ 3.94	$ 2.01
Diluted (in dollars per share)		$ 4.98	$ 3.91	$ 1.99
Shares used in computing net income attributable to Fiserv, Inc. per share:
Basic (in shares)		611.7	642.3	662.6
Diluted (in shares)		615.9	647.9	671.6
Processing and services
Revenue:
Total revenue	[1]	$ 15,630	$ 14,460	$ 13,307
Expenses:
Cost of goods and services sold		5,332	5,771	6,084
Product
Revenue:
Total revenue		3,463	3,277	2,919
Expenses:
Cost of goods and services sold		$ 2,338	$ 2,221	$ 2,044

[1] Includes processing and other fees charged to related party investments accounted for under the equity method of $178 million, $201 million and $203 million for the years ended December 31, 2023, 2022 and 2021, respectively (see Note 19).