Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue		$ 3,465	$ 1,512	$ 7,234	$ 3,014
Selling, general and administrative		1,377	343	2,781	684
(Gain) loss on sale of businesses		3	0	(428)	(10)
Total expenses		3,300	1,128	6,440	2,257
Operating income		165	384	794	757
Interest expense, net		(174)	(58)	(361)	(115)
Debt financing activities		0	(37)	0	(96)
Other income		1	2	21	3
Income (loss) before income taxes and loss from investments in unconsolidated affiliates		(8)	291	454	549
Income tax (provision) benefit		27	(60)	(52)	(91)
Loss from investments in unconsolidated affiliates		(10)	(8)	(16)	(10)
Net income		9	223	386	448
Net income (loss) attributable to noncontrolling interests and redeemable noncontrolling interests		7	0	(8)	0
Net income attributable to Fiserv, Inc.		$ 2	$ 223	$ 394	$ 448
Net income attributable to Fiserv, Inc. per share – basic (in dollars per share)		$ 0	$ 0.57	$ 0.58	$ 1.14
Net income attributable to Fiserv, Inc. per share – diluted (in dollars per share)		$ 0	$ 0.56	$ 0.57	$ 1.12
Shares used in computing net income attributable to Fiserv, Inc. per share:
Basic (in shares)		670.0	392.5	674.1	392.1
Diluted (in shares)		680.8	399.6	686.0	399.4
Related Party Fees | Equity investments
Shares used in computing net income attributable to Fiserv, Inc. per share:
Processing, administrative, and other fees		$ 55	$ 9	$ 112	$ 18
Processing and services
Revenue	[1]	2,890	1,328	5,965	2,621
Cost of goods sold and services		1,466	617	3,101	1,241
Product
Revenue		575	184	1,269	393
Cost of goods sold and services		$ 454	$ 168	$ 986	$ 342

[1] Includes processing and other fees charged to related party investments accounted for under the equity method of $55 million and $9 million for the three months ended June 30, 2020 and 2019, respectively, and $112 million and $18 million for the six months ended June 30, 2020 and 2019, respectively (see Note 21).