Stock-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Stock-based compensation
Pre-tax compensation expense	$ 16	$ 8
Long-term stock awards
Stock-based compensation
Pre-tax compensation expense	4	5
Stock options
Stock-based compensation
Pre-tax compensation expense	3	1
Restricted stock units
Stock-based compensation
Pre-tax compensation expense	8	0
Performance Restricted Stock Units
Stock-based compensation
Pre-tax compensation expense	1	1
Phantom stock awards and stock appreciation rights
Stock-based compensation
Pre-tax compensation expense	$ 0	$ 1