Benefit Plans - Changes not yet recognized (Details) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($)
Pension benefits
Change in items not yet recognized as a component of defined benefit plans, net periodic cost
Items not yet recognized as a component of net cost – December 31, 2019	$ (142)
Prior service credit arising during the period	0
Prior service credit recognized during the period due to curtailment	10
Prior service credit amortized to net cost	54
Translation adjustment and other	0
Items not yet recognized as a component of net cost – December 31, 2020	(78)
Postretirement benefits
Change in items not yet recognized as a component of defined benefit plans, net periodic cost
Items not yet recognized as a component of net cost – December 31, 2019	(13)
Prior service credit arising during the period	(102)
Prior service credit recognized during the period due to curtailment	18
Prior service credit amortized to net cost	10
Translation adjustment and other	(2)
Items not yet recognized as a component of net cost – December 31, 2020	$ (89)

No definition available.

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- Definition

Amount, before tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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- Definition

Amount, before tax, of reclassification adjustment from accumulated other comprehensive (income) loss for prior service cost (credit) of defined benefit plan.

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Amount, before tax, of increase (decrease) to other comprehensive income from settlement and curtailment gain (loss) of defined benefit plan.

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Amount before tax, after reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount, before tax, of gain (loss) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

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