Acquisitions and Dispositions - Narrative (Details) - USD ($) $ in Millions						2 Months Ended	3 Months Ended				6 Months Ended
	Jun. 30, 2021	May 04, 2021	Feb. 02, 2021	Jan. 22, 2021	Feb. 18, 2020	May 11, 2021	Jun. 30, 2021	Jun. 14, 2021	Sep. 30, 2020	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Business Acquisition [Line Items]
Goodwill	$ 36,668						$ 36,668				$ 36,668		$ 36,322
Tax expense												$ 112
Net pre-tax gain							42			$ (10)	58	(16)
Tax expense							228			$ (27)	246	$ 52
Banc of America Merchant Services | Corporate joint venture
Business Acquisition [Line Items]
Percentage of interest in joint venture										51.00%		51.00%
Banc of America Merchant Services Joint Venture | Bank Of America
Business Acquisition [Line Items]
Processing and other support services agreement, term (in years)									5 years
Investment Services Business
Business Acquisition [Line Items]
Controlling interest sold (as a percent)					60.00%
Percentage of interest owned in affiliate					40.00%
InvestCloud
Business Acquisition [Line Items]
Capital contribution			$ 200
Net pre-tax gain											28
Tax expense											6
Disposal Group, Disposed of by Sale
Business Acquisition [Line Items]
Consideration from sale of business					$ 584
Tax expense												$ 112
Revaluation/Remeasurement gain												176
Disposal Group, Disposed of by Sale | Investment Services Business
Business Acquisition [Line Items]
Controlling interest sold (as a percent)					60.00%
Pre-tax gain on sale												$ 428
Disposal Group, Disposed of by Sale | InvestCloud
Business Acquisition [Line Items]
Tax expense							8
Proceeds from sale of entire ownership interest	$ 466
Pre-tax gain on sale							33
Ondot
Business Acquisition [Line Items]
Payments for acquisitions of businesses				$ 271
Acquired cash				13
Pre-tax gain from remeasurement											$ 12
Measurement period adjustments, decrease in goodwill							33
Measurement period adjustments, deferred income taxes							12
Intangible assets				142
Goodwill				177
Ondot | Acquired software and technology
Business Acquisition [Line Items]
Measurement period adjustments, increase in intangible assets							30
Intangible assets				90
Ondot | Customer relationships
Business Acquisition [Line Items]
Measurement period adjustments, increase in intangible assets							$ 15
Intangible assets				35
Ondot | Non-compete agreements and other
Business Acquisition [Line Items]
Intangible assets				$ 17
Pineapple Payments
Business Acquisition [Line Items]
Payments for acquisitions of businesses		$ 206
Acquired cash		6
Earn-out provisions estimated fair value		30
Intangible assets		81
Goodwill		124
Goodwill, expected tax deductible amount		$ 90
SpendLabs and Radius8
Business Acquisition [Line Items]
Payments for acquisitions of businesses								$ 49
Intangible assets								20
Goodwill								$ 30
MerchantPro, Bypass, and Inlet
Business Acquisition [Line Items]
Payments for acquisitions of businesses						$ 167
Acquired cash						2
Earn-out provisions estimated fair value						45
Intangible assets						81
Goodwill						90
Goodwill, expected tax deductible amount						36
Net assumed liabilities						4
MerchantPro, Bypass, and Inlet | Acquired software and technology
Business Acquisition [Line Items]
Intangible assets						14
MerchantPro, Bypass, and Inlet | Customer relationships
Business Acquisition [Line Items]
Intangible assets						$ 32