Pensions and Other Benefits - Changes in Fair Value of Pension Plan and Other Benefit Plan Level 3 Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Pension Benefits
Pension Plan Assets [Roll Forward]
Balance at beginning of period	$ 324	$ 317
Transfers in and/or out of Level 3	(269)	0
Actual return on plan assets:
Realized gain	3	2
Net unrealized loss	2	(9)
Purchases, sales, issuances and settlements:
Purchases	24	17
Sales	(30)	(3)
Balance at end of period	54	324
Other Benefits
Pension Plan Assets [Roll Forward]
Balance at beginning of period	35	35
Transfers in and/or out of Level 3	(35)	0
Actual return on plan assets:
Realized gain	0	0
Net unrealized loss	1	0
Purchases, sales, issuances and settlements:
Purchases	39	2
Sales	(1)	(2)
Balance at end of period	$ 39	$ 35