Equity (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member		us-gaap:AccountingStandardsUpdate201613Member
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 33,028	$ 2,546	$ 34,595	$ 2,293	$ 2,293
Net income (loss)	265	221	633	669
Net adjustment to noncontrolling interests from dissolution	(762)		(762)
Measurement period adjustments related to First Data Acquisition			(126)
Shares issued to acquire First Data		31,179		31,179
Distributions paid to noncontrolling interests		(51)	(30)	(51)
Other comprehensive income (loss)	(170)	(186)	(623)	(312)
Share-based compensation	84	87	286	121
Shares issued under stock plans	(16)	0	(64)	17
Purchases of treasury stock		(36)	(1,435)	(156)
Balance at end of period	32,429	33,760	32,429	33,760	$ 34,595
Net income attributable to redeemable noncontrolling interest	$ 11	$ 4	29	$ 4
Distributions paid to redeemable noncontrolling interests			$ 31
Common Shares
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period (in shares)	791	791	791	791	791
Balance at beginning of period	$ 8	$ 8	$ 8	$ 8	$ 8
Balance at end of period (in shares)	791	791	791	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)	122	399	112	399	399
Balance at beginning of period	$ (4,429)	$ (10,408)	$ (3,118)	$ (10,340)	$ (10,340)
Shares issued to acquire First Data (in shares)		(286)		(286)
Shares issued to acquire First Data		$ 7,478		$ 7,478
Shares issued under stock plans (in shares)	(1)	(2)	(5)	(4)
Shares issued under stock plans	$ 32	$ 57	$ 156	$ 109
Purchases of treasury stock (in shares)		0	14	2
Purchases of treasury stock		$ (36)	$ (1,435)	$ (156)
Balance at end of period (in shares)	121	111	121	111	112
Balance at end of period	$ (4,397)	$ (2,909)	$ (4,397)	$ (2,909)	$ (3,118)
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	23,771	1,056	23,741	1,057	1,057
Net adjustment to noncontrolling interests from dissolution	(36)		(36)
Shares issued to acquire First Data		22,582		22,582
Share-based compensation	84	87	286	121
Shares issued under stock plans	(48)	(57)	(220)	(92)
Balance at end of period	23,771	23,668	23,771	23,668	23,741
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(644)	(193)	(180)	(67)	(67)
Other comprehensive income (loss)	(187)	(186)	(651)	(312)
Balance at end of period	(831)	(379)	(831)	(379)	(180)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	12,877	12,083	12,528	11,635	11,635
Net income (loss)	264	198	658	646
Balance at end of period	13,141	12,281	13,141	12,281	12,528
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	1,445	0	1,616	0	0
Net income (loss)	1	23	(25)	23
Net adjustment to noncontrolling interests from dissolution	(726)		(726)
Measurement period adjustments related to First Data Acquisition			(126)
Shares issued to acquire First Data		1,119		1,119
Distributions paid to noncontrolling interests		(51)	(30)	(51)
Other comprehensive income (loss)	17		28
Balance at end of period	$ 737	$ 1,091	737	$ 1,091	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)