Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 276	$ 225	$ 662	$ 673
Other comprehensive (loss) income:
Fair market value adjustment on cash flow hedges, net of income tax (provision) benefit of ($2 million), $1 million, $0 million and $46 million	6	(4)	1	(134)
Reclassification adjustment for net realized losses on cash flow hedges included in net interest expense, net of income tax provision of $1 million, $1 million, $4 million and $2 million	4	4	12	6
Foreign currency translation	(180)	(186)	(636)	(184)
Total other comprehensive loss	(170)	(186)	(623)	(312)
Comprehensive income	106	39	39	361
Less: net income attributable to noncontrolling interests and redeemable noncontrolling interests	12	27	4	27
Less: other comprehensive income attributable to noncontrolling interests	17	0	28	0
Comprehensive income attributable to Fiserv, Inc.	$ 77	$ 12	$ 7	$ 334