Stock-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock-based compensation
Pre-tax compensation expense	$ 9	$ 8	$ 35	$ 24
Long-term stock awards
Stock-based compensation
Pre-tax compensation expense	4	6	11	16
Stock options
Stock-based compensation
Pre-tax compensation expense	1	1	6	3
Restricted stock units
Stock-based compensation
Pre-tax compensation expense	1	0	12	0
Performance Restricted Stock Units
Stock-based compensation
Pre-tax compensation expense	2	0	3	2
Phantom stock awards and stock appreciation rights
Stock-based compensation
Pre-tax compensation expense	$ 1	$ 1	$ 3	$ 3