Employee Benefit Plans - Changes in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Change in plan assets:
Fair value of plan assets as of January 1,	$ 280
Fair value of plan assets as of December 31,	279	$ 280
Defined Pension  Benefits
Change in benefit obligation:
Accumulated benefit obligation as of January 1,	178	165
Service cost	1	1
Interest cost	4	5
Benefits paid	(12)	(11)
Actuarial loss (gain)	(8)	18
Accumulated benefit obligation as of December 31,	163	178
Change in plan assets:
Fair value of plan assets as of January 1,	274	254
Actual return on plan assets	10	30
Employer contributions	1	1
Benefits paid	(12)	(11)
Fair value of plan assets as of December 31,	273	274
Over (under) funded status as of December 31,	110	96
Other Postretirement Benefits
Change in benefit obligation:
Accumulated benefit obligation as of January 1,	21	27
Service cost	0	0
Interest cost	0	1
Benefits paid	(2)	(2)
Actuarial loss (gain)	(3)	(5)
Accumulated benefit obligation as of December 31,	16	21
Change in plan assets:
Fair value of plan assets as of January 1,	6	6
Actual return on plan assets	1	1
Employer contributions	1	1
Benefits paid	(2)	(2)
Fair value of plan assets as of December 31,	6	6
Over (under) funded status as of December 31,	$ (10)	$ (15)