Employee Benefits - Change in Plan Assets Measured at Fair Value (Details) - Combined Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Change in plan assets
Fair value of plan assets at beginning of year	$ 8,531	$ 10,546
Fair value of plan assets at end of year	4,715	8,531
Level 3
Change in plan assets
Fair value of plan assets at beginning of year	11	8
Dispositions	(5)
Actual return on plan assets	(1)	3
Fair value of plan assets at end of year	5	11
Level 3 | High Yield Bonds
Change in plan assets
Fair value of plan assets at beginning of year	6	6
Dispositions	(1)
Actual return on plan assets	(1)	0
Fair value of plan assets at end of year	4	6
Level 3 | U.S. Stocks
Change in plan assets
Fair value of plan assets at beginning of year	5	2
Dispositions	(4)
Actual return on plan assets	0	3
Fair value of plan assets at end of year	$ 1	$ 5