Investments - Summary of Derivative Instruments Held (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Designated as Hedging Instrument | Fair Value Hedging | Foreign currency swap contracts
Derivative [Line Items]
Notional value	$ 817	$ 817
Designated as Hedging Instrument | Net Investment Hedging | Foreign currency swap contracts
Derivative [Line Items]
Notional value	526	438
Designated as Hedging Instrument | Net Investment Hedging | Foreign currency forward contracts
Derivative [Line Items]
Notional value	426	406
Not Designated as Hedging Instrument | Foreign currency forward contracts
Derivative [Line Items]
Notional value	$ 439	$ 410