Pension Plans and Other Postretirement Benefits - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer contributions	$ 552	$ 520	$ 550
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	78	25	25
Multiemployer plans, plan contributions	19	19	18
Benefit obligation	6,009	6,462	6,239
Net periodic benefit cost	$ (186)	(218)	(131)
Pension Plan \| Equity securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocations	12.00%
Pension Plan \| Debt securities
Defined Benefit Plan Disclosure [Line Items]
Target investment allocations	77.00%
Pension Plan \| Real Estate Investment
Defined Benefit Plan Disclosure [Line Items]
Target investment allocations	5.00%
Pension Plan \| Private equity investments
Defined Benefit Plan Disclosure [Line Items]
Target investment allocations	3.00%
Pension Plan \| Hedge Funds
Defined Benefit Plan Disclosure [Line Items]
Target investment allocations	3.00%
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Multiemployer plans, plan contributions	$ 60	54	57
Benefit obligation	207	226
Net periodic benefit cost	$ 4	$ 12	$ 7

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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