Acquisitions and Dispositions - Purchase Price Allocation (Details) $ in Millions	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jul. 29, 2019 USD ($) entity
Business Acquisition [Line Items]
Goodwill	$ 35,908	$ 36,038
Number of entities to dispose | entity			2
First Data
Business Acquisition [Line Items]
Cash and cash equivalents			$ 310
Trade accounts receivable			1,747
Prepaid expenses and other current assets			1,047
Settlement assets			10,398
Property and equipment			1,156
Finite-lived intangibles assets			16,272
Goodwill			30,811
Investments in unconsolidated affiliates			2,676
Other long-term assets			1,191
Total assets acquired			65,608
Accounts payable and accrued expenses			1,613
Short-term and current maturities of long-term debt			243
Contract liabilities			71
Settlement obligations			10,398
Deferred income taxes			3,671
Long-term contract liabilities			16
Long-term debt and other long-term liabilities			1,261
Total liabilities assumed			17,273
Net assets acquired			48,335
Redeemable noncontrolling interests			252
Noncontrolling interests			1,608
Total purchase price			46,475
Customer relationships | First Data
Business Acquisition [Line Items]
Finite-lived intangibles assets			13,458
Other intangible assets | First Data
Business Acquisition [Line Items]
Finite-lived intangibles assets			$ 2,814