Derivative Instruments - Notional Amount of Derivatives Outstanding (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Notional amount	$ 4,893	$ 8,231
Foreign Exchange Contract | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional amount	2,710	3,517
Cash Flow Hedging | Foreign Exchange Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional amount	1,983	1,510
Net Investment Hedging | Foreign Exchange Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional amount	200	804
Fair Value Hedging | Interest Rate Contract | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional amount	$ 0	$ 2,400