Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue		$ 4,873	$ 4,518	$ 14,176	$ 13,106
Selling, general and administrative		1,652	1,547	4,952	4,560
Net (gain) loss on sale of businesses and other assets		(176)	120	(172)	(27)
Total expenses		3,370	3,663	10,608	10,545
Operating income		1,503	855	3,568	2,561
Interest expense, net		(258)	(190)	(692)	(534)
Other expense, net		(35)	(13)	(81)	(83)
Income before income taxes and (loss) income from investments in unconsolidated affiliates		1,210	652	2,795	1,944
Income tax provision		(239)	(147)	(544)	(382)
(Loss) income from investments in unconsolidated affiliates		(2)	(12)	(11)	222
Net income		969	493	2,240	1,784
Less: net income attributable to noncontrolling interests and redeemable noncontrolling interests		17	12	42	36
Net income attributable to Fiserv, Inc.		$ 952	$ 481	$ 2,198	$ 1,748
Net income attributable to Fiserv, Inc. per share:
Basic (in dollars per share)		$ 1.57	$ 0.75	$ 3.57	$ 2.71
Diluted (in dollars per share)		$ 1.56	$ 0.75	$ 3.54	$ 2.68
Shares used in computing net income attributable to Fiserv, Inc. per share:
Basic (in shares)		606.2	639.6	616.2	645.2
Diluted (in shares)		610.3	645.0	620.3	651.0
Processing and services
Revenue	[1]	$ 4,008	$ 3,678	$ 11,605	$ 10,738
Cost of goods sold and services		1,311	1,443	4,067	4,381
Product
Revenue		865	840	2,571	2,368
Cost of goods sold and services		$ 583	$ 553	$ 1,761	$ 1,631

[1] Includes processing and other fees charged to related party investments accounted for under the equity method of $45 million and $51 million for the three months ended September 30, 2023 and 2022, respectively, and $136 million and $151 million for the nine months ended September 30, 2023 and 2022, respectively (see Note 19).