Stock-Based Compensation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock-based compensation
Pre-tax compensation expense	$ 12	$ 10	$ 42	$ 26
Long-term stock awards
Stock-based compensation
Pre-tax compensation expense	3	3	6	7
Stock options
Stock-based compensation
Pre-tax compensation expense	1	2	5	5
Restricted stock units
Stock-based compensation
Pre-tax compensation expense	4	3	23	11
Performance Restricted Stock Units
Stock-based compensation
Pre-tax compensation expense	4	0	6	1
Phantom stock awards
Stock-based compensation
Pre-tax compensation expense	$ 0	$ 2	$ 2	$ 2