Pension, Other Postretirement Benefits and Savings Plans - Selected Pension Plan Information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
United States
All plans:
Accumulated benefit obligation	$ 5,220	$ 4,994
Plans not fully-funded:
Projected benefit obligation	5,235	5,009
Accumulated benefit obligation	5,220	4,994
Fair value of plan assets	4,970	4,780
Non-U.S.
All plans:
Accumulated benefit obligation	3,284	3,097
Plans not fully-funded:
Projected benefit obligation	933	1,059
Accumulated benefit obligation	856	991
Fair value of plan assets	$ 185	$ 370

Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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Amount of projected benefit obligation for defined benefit pension plan with accumulated benefit obligation in excess of plan assets.

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