Equity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 32,532	$ 33,028	$ 33,070	$ 34,595
Net income (loss)	435	265	1,015	633
Measurement period adjustments related to First Data acquisition				(126)
Distributions paid to noncontrolling interests	0		(1)	(30)
Net adjustment to noncontrolling interests from dissolution		(762)		(762)
Other comprehensive income (loss)	(344)	(170)	(287)	(623)
Share-based compensation	63	84	190	286
Shares issued under stock plans	3	(16)	(98)	(64)
Purchases of treasury stock	(365)		(1,565)	(1,435)
Retirement of treasury stock			0
Accounting Standards Update [Extensible List]					Accounting Standards Update 2016-13
Balance at end of period	32,324	32,429	32,324	32,429	$ 34,595
Net income attributable to redeemable noncontrolling interest	11	$ 11	33	29
Distributions paid to redeemable noncontrolling interests	12		32	$ 31
Distributions to BANA related to the BAMS dissolution	$ 8		$ 8
Common Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period (in shares)	784	791	789	791
Balance at beginning of period	$ 8	$ 8	$ 8	$ 8
Retirement of treasury stock (in shares)			(5)
Balance at end of period (in shares)	784	791	784	791	791
Balance at end of period	$ 8	$ 8	$ 8	$ 8	$ 8
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period (in shares)	123	122	121	112
Balance at beginning of period	$ (4,866)	$ (4,429)	$ (4,375)	$ (3,118)
Shares issued under stock plans (in shares)	(2)	(1)	(5)	(5)
Shares issued under stock plans	$ 52	$ 32	$ 173	$ 156
Purchases of treasury stock (in shares)	3		13	14
Purchases of treasury stock	$ (365)		$ (1,565)	$ (1,435)
Retirement of treasury stock (in shares)			(5)
Retirement of treasury stock			$ 588
Balance at end of period (in shares)	124	121	124	121	112
Balance at end of period	$ (5,179)	$ (4,397)	$ (5,179)	$ (4,397)	$ (3,118)
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	22,960	23,771	23,643	23,741
Net adjustment to noncontrolling interests from dissolution		(36)		(36)
Share-based compensation	63	84	190	286
Shares issued under stock plans	(49)	(48)	(271)	(220)
Retirement of treasury stock			(588)
Balance at end of period	22,974	23,771	22,974	23,771	23,741
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(323)	(644)	(387)	(180)
Other comprehensive income (loss)	(326)	(187)	(262)	(651)
Balance at end of period	(649)	(831)	(649)	(831)	(180)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	14,014	12,877	13,441	12,528
Net income (loss)	428	264	1,001	658
Balance at end of period	14,442	13,141	14,442	13,141	12,528
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	739	1,445	740	1,616
Net income (loss)	7	1	14	(25)
Measurement period adjustments related to First Data acquisition				(126)
Distributions paid to noncontrolling interests	0		(1)	(30)
Net adjustment to noncontrolling interests from dissolution		(726)		(726)
Other comprehensive income (loss)	(18)	17	(25)	28
Balance at end of period	$ 728	$ 737	$ 728	737	1,616
Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period				(45)
Balance at end of period					(45)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period				$ (45)
Balance at end of period					$ (45)