Pensions and Other Benefits - Amounts Recognized in Accumulated Other Comprehensive Loss (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)
Prior Service Cost | Pension Benefits
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	$ 14
Amortization	(2)
Activity	0
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	12
Prior Service Cost | Other Benefits
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	(103)
Amortization	29
Activity	0
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	(74)
Actuarial (gains) losses | Pension Benefits
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	1,764
Amortization	(231)
Activity	(237)
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	1,296
Actuarial (gains) losses | Other Benefits
Accumulated Other Comprehensive Income [Roll Forward]
Defined Benefit Plan costs in Accumulated Other Comprehensive, beginning balance	(556)
Amortization	23
Activity	(160)
Defined Benefit Plan costs in Accumulated Other Comprehensive, ending balance	$ (693)