Pension and Postretirement Benefit Plans - US Pension Weighted Averages and Expected Returns Information (Details) - Funded - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020
Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	$ 207	$ 366
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	$ 4
Weighted-average assumptions used to determine benefit obligations
Discount rate	3.27%	4.41%	3.79%
Percentage increase (decrease) in discount rate obligation from the prior year	(1.14%)
Weighted-average assumptions used to determine net cost for years ended
Discount rate - service cost	4.53%	3.86%	4.50%
Discount rate - interest cost	4.15%	3.52%	3.80%
Expected return on assets	6.43%	6.53%	6.48%
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	$ 101	$ 254
Weighted-average assumptions used to determine benefit obligations
Discount rate	3.25%	4.36%	3.68%
Compensation rate increase	3.21%	4.10%	4.10%
Percentage increase (decrease) in discount rate obligation from the prior year	(1.11%)
Impact to the Projected Benefit Obligation (PBO) as a result of a change in discount rate	$ 2,000
Weighted-average assumptions used to determine net cost for years ended
Discount rate - service cost	4.44%	3.78%	4.42%
Discount rate - interest cost	4.02%	3.35%	3.61%
Expected return on assets	7.00%	7.25%	7.25%
Compensation rate increase	4.10%	4.10%	4.10%
International | Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company contributions	$ 106	$ 112
Weighted-average assumptions used to determine benefit obligations
Discount rate	1.81%	2.50%	2.41%
Compensation rate increase	2.88%	2.89%	2.89%
Weighted-average assumptions used to determine net cost for years ended
Discount rate - service cost	2.39%	2.27%	2.32%
Discount rate - interest cost	2.26%	2.14%	2.25%
Expected return on assets	4.90%	5.02%	5.16%
Compensation rate increase	2.89%	2.89%	2.90%
Qualified | United States | Qualified and Non-qualified Pension Benefits
Asset Allocation assumption
Rate of return on plan assets	16.30%	(0.50%)	12.40%
Average annual actual return on plan assets over the past 10 years	8.90%
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	9.40%
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	6.75%
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	7.00%
Qualified | United States | Qualified and Non-qualified Pension Benefits | Global equity
Asset Allocation assumption
Asset allocation assumption for next fiscal year				23.00%
Qualified | United States | Qualified and Non-qualified Pension Benefits | Private equity
Asset Allocation assumption
Asset allocation assumption for next fiscal year				14.00%
Qualified | United States | Qualified and Non-qualified Pension Benefits | Fixed income
Asset Allocation assumption
Asset allocation assumption for next fiscal year				47.00%
Qualified | United States | Qualified and Non-qualified Pension Benefits | Absolute return
Asset Allocation assumption
Asset allocation assumption for next fiscal year				16.00%