Pension and Postretirement Benefit Plans - US Pension Weighted Averages and Expected Returns Information (Details) - Funded - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	$ 153	$ 207
Qualified and Non-qualified Pension Benefits \| Maximum
Asset Allocation assumption
Estimated pension contributions for next fiscal year	200
Qualified and Non-qualified Pension Benefits \| Minimum
Asset Allocation assumption
Estimated pension contributions for next fiscal year	100
Postretirement Benefits
Benefit Plan Information
Company contributions	$ 3	$ 3
Weighted-average assumptions used to determine benefit obligations
Discount rate	2.50%	3.27%	4.41%
Percentage increase (decrease) in discount rate obligation from the prior year	(0.77%)
Weighted-average assumptions used to determine net cost for years ended
Discount rate - service cost	3.45%	4.53%	3.86%
Discount rate - interest cost	3.00%	4.15%	3.52%
Expected return on assets	6.32%	6.43%	6.53%
United States
Weighted-average assumptions used to determine benefit obligations
Original percentage medical inflation indexation by company in year	3.00%
Revised percentage medical inflation indexation by company in year	1.50%
United States \| Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	$ 61	$ 101
Weighted-average assumptions used to determine benefit obligations
Discount rate	2.55%	3.25%	4.36%
Compensation rate increase	3.21%	3.21%	4.10%
Percentage increase (decrease) in discount rate obligation from the prior year	(0.70%)
Weighted-average assumptions used to determine net cost for years ended
Discount rate - service cost	3.41%	4.44%	3.78%
Discount rate - interest cost	2.87%	4.02%	3.35%
Expected return on assets	6.75%	7.00%	7.25%
Compensation rate increase	3.21%	4.10%	4.10%
United States \| Pension and Postretirement Benefit plans
Weighted-average assumptions used to determine benefit obligations
Impact to the Projected Benefit Obligation (PBO) as a result of a change in discount rate	$ 1,800
International \| Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	$ 92	$ 106
Weighted-average assumptions used to determine benefit obligations
Discount rate	1.38%	1.81%	2.50%
Compensation rate increase	2.88%	2.88%	2.89%
Weighted-average assumptions used to determine net cost for years ended
Discount rate - service cost	1.61%	2.39%	2.27%
Discount rate - interest cost	1.61%	2.26%	2.14%
Expected return on assets	4.70%	4.90%	5.02%
Compensation rate increase	2.88%	2.89%	2.89%
Qualified \| United States \| Qualified and Non-qualified Pension Benefits
Asset Allocation assumption
Rate of return on plan assets	13.60%	16.30%	(0.50%)
Average annual actual return on plan assets over the past 10 years	8.80%
Number years of used in the calculation of one average annual actual return on plan assets	10 years
Average annual actual return on plan assets over the past 25 years	9.00%
Number years of used in the calculation of a second average annual actual return on plan assets	25 years
Company's assumption for the expected return on plan assets
Expected return on assets for next fiscal year	6.50%
Qualified \| United States \| Qualified and Non-qualified Pension Benefits \| Primary U.S. Qualified Pension Plan
Company's assumption for the expected return on plan assets
Expected return on assets	6.75%
Qualified \| United States \| Qualified and Non-qualified Pension Benefits \| Global equity
Asset Allocation assumption
Asset allocation assumption for next fiscal year	22.00%
Qualified \| United States \| Qualified and Non-qualified Pension Benefits \| Private equity
Asset Allocation assumption
Asset allocation assumption for next fiscal year	12.00%
Qualified \| United States \| Qualified and Non-qualified Pension Benefits \| Fixed income
Asset Allocation assumption
Asset allocation assumption for next fiscal year	49.00%
Qualified \| United States \| Qualified and Non-qualified Pension Benefits \| Absolute return
Asset Allocation assumption
Asset allocation assumption for next fiscal year	17.00%

The impact to the Projected Benefit Obligation (PBO) as a result of a change in the discount rate.

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- Definition

Percentage, expected long-term rate of return on securities for next fiscal year.

+ References

No definition available.

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- Definition

Percentage, expected long-term rate of return on securities.

+ References

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- Definition

This element represents the actual return on the plan assets.

+ References

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- Definition

This element represents the interest rate used to adjust for time value of money for interest costs.

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- Definition

The number years of used in the calculation of one average annual actual return on plan assets.

+ References

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- Definition

The number years of used in the calculation of a second average annual actual return on plan assets.

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- Definition

The average annual actual return on plan assets over the past ten years, percentage.

+ References

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- Definition

The average annual actual return on plan assets over the past twenty-five years, percentage.

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- Definition

This element represents the percentage change in assumed discount rate from the prior year used in calculating the benefit obligation.

+ References

No definition available.

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- Definition

The original percentage that the Company would credit the Retiree Medical Saving Account and the Medicare Health Reimbursement Arrangement as an inflation indexation.

+ References

No definition available.

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- Definition

The revised percentage that the Company would credit the Retiree Medical Savings Account and the Medicare Health Reimbursement arrangement as an inflation indexation.

+ References

No definition available.

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- References

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan.

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- Definition

Weighted average rate increase of compensation, used to determine benefit obligation of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

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- Definition

Weighted average rate for present value of future retirement benefits cash flows, used to determine net periodic benefit cost of defined benefit plan.

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

+ References

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- Definition

Weighted average rate of compensation increase used to determine net periodic benefit cost of defined benefit plan. Plan includes, but is not limited to, pay-related defined benefit plan.

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of contribution expected to be received by defined benefit plan from employer in next fiscal year following current fiscal year.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

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