Fair Value - Fair Value Inputs, Assets and Liabilities, Quantitative Information (Details) - Pricing Methods with Significant Unobservable Market Inputs (Level 3) $ in Millions	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Significant Unobservable Inputs Readily Available
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Total, derivative asset	$ 4	$ 4
Total liabilities carried at fair value	3	4
Significant Unobservable Inputs Readily Available | Derivative instruments, liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, derivative asset	3	4
Significant Unobservable Inputs Readily Available | Derivative instruments, assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, derivative asset	$ 4	$ 4
Volatility | Option model | Derivative instruments, liabilities | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative liability, measurement input	0.073	0.114
Volatility | Option model | Derivative instruments, assets | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative asset, measurement input	0.078	0.114