Annual report pursuant to Section 13 and 15(d)

COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Additional Information (Detail)

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COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Additional Information (Detail)
 3 Months Ended 12 Months Ended
Dec. 31, 2020
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Sep. 30, 2020
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Jun. 30, 2020
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Mar. 31, 2020
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Dec. 31, 2019
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Employee
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Sep. 30, 2019
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Jun. 30, 2019
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Mar. 31, 2019
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Dec. 31, 2020
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Dec. 31, 2019
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Employee
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Dec. 31, 2018
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Defined Benefit Plan Disclosure [Line Items]                      
Defined benefit plan net actuarial loss                 $ (10,100,000,000) $ (8,000,000,000.0)  
Service cost discount rate                 2.87% 3.55% 4.45%
Number of covered persons | Employee         18,800         18,800  
Lump Sum Pension Payments         $ 820,000,000            
Health care cost trends, initial annual rate increase 6.50%               6.50%    
Health care cost trends, an ultimate trend rate 4.50%               4.50%    
Employer contributions                 $ 3,125,000,000 $ 2,362,000,000 $ 186,000,000
Fair value of plan assets $ 54,881,000,000       47,767,000,000       54,881,000,000 47,767,000,000  
Decreas in projected benefit obligation                   900,000,000  
Change in unrecognized pension and postretirement benefit costs, net of tax                 880,000,000 1,129,000,000 (272,000,000)
Net Income $ (3,347,000,000) $ 1,957,000,000 $ 1,768,000,000 $ 965,000,000 $ (106,000,000) $ 1,750,000,000 $ 1,685,000,000 $ 1,111,000,000 $ 1,343,000,000 $ 4,440,000,000 4,791,000,000
Common stock held in plan assets (in shares) | shares 0       0       0 0  
Pension and postretirement benefit expense                 $ 7,125,000,000 $ 3,141,000,000 2,242,000,000
Pension and postretirement benefit expense                 7,125,000,000 3,141,000,000 2,242,000,000
Private Equity and Real Estate | Other Investments [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Unfunded commitments to limited partnerships $ 3,300,000,000               3,300,000,000    
Pension Benefits                      
Defined Benefit Plan Disclosure [Line Items]                      
Accumulated benefit obligation for pension plans 66,900,000,000       $ 55,000,000,000.0       66,900,000,000 55,000,000,000.0  
Employer contributions                 26,000,000 27,000,000  
Postretirement Medical Benefits                      
Defined Benefit Plan Disclosure [Line Items]                      
Employer contributions                 77,000,000 82,000,000  
Postemployment Retirement Benefits                      
Defined Benefit Plan Disclosure [Line Items]                      
Accumulated benefit obligation for pension plans 2,800,000,000       2,600,000,000       2,800,000,000 2,600,000,000  
International Pension Benefits                      
Defined Benefit Plan Disclosure [Line Items]                      
Fair value of plan assets 1,835,000,000       1,558,000,000       1,835,000,000 1,558,000,000  
International Pension Benefits | Cash and Cash Equivalents [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Fair value of plan assets $ 84,000,000       $ 72,000,000       84,000,000 72,000,000  
International Pension Benefits | Pension Benefits                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined benefit plan, curtailment                 0 0 0
Defined benefit plan net actuarial loss                 $ (123,000,000) $ (213,000,000)  
Discount rate 1.94%       2.21%       1.94% 2.21%  
Projected benefit obligation, Projected Benefit Obligation Exceeds the Fair Value of the Plan Assets $ 845,000,000       $ 1,319,000,000       $ 845,000,000 $ 1,319,000,000  
Pension obligations 388,000,000       377,000,000       388,000,000 377,000,000  
Fair value of plan assets $ 1,835,000,000       $ 1,558,000,000       $ 1,835,000,000 1,558,000,000 1,284,000,000
Change in Assumptions for Defined Benefit Plans [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Change in unrecognized pension and postretirement benefit costs, net of tax                   810,000,000  
Net Income                   $ 616,000,000  
Earnings Per Share, Basic and Diluted | $ / shares                   $ 0.71  
Discounted Employee Stock Purchase Modified Plan [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Share Based Compensation Arrangement By Share Based Payment Award Exercisable Price Percentage Of Closing Price Of Another Class Of Stock 95.00%               95.00%    
Employee Defined Contribution Plans [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Contributions charged to expense                 $ 139,000,000 $ 130,000,000 127,000,000
Pension and postretirement benefit expense                 84,000,000 67,000,000 28,000,000
Pension and postretirement benefit expense                 84,000,000 67,000,000 28,000,000
Amended Employee Defined Contribution Plans                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined Contribution Plan, Increase (Decrease), Cost                 0 0 0
Defined Contribution Plan, Increase (Decrease), Cost                 0 0 0
Defined Contribution Money Purchase Plans [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Contributions charged to expense                 107,000,000 97,000,000 $ 92,000,000
Central States, South East & South West Areas Health and Welfare Fund | Pension Benefits                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined benefit plan net actuarial loss                 (2,300,000,000) $ (603,000,000)  
Multiemployer Plans, Withdrawal Obligation                 6,100,000,000    
Increase in benefit obligation                 2,300,000,000    
Pension obligations $ 5,500,000,000               $ 5,500,000,000    
Minimum                      
Defined Benefit Plan Disclosure [Line Items]                      
Duration for unfunded commitments to be contributed 3 years               3 years    
Minimum | Private Equity and Real Estate | Other Investments [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Redemption notice period, lower limit                 10 years    
Minimum | U.S. Pension Benefits                      
Defined Benefit Plan Disclosure [Line Items]                      
Postretirement medical plans service minimum eligibility year                 10 years    
Postretirement medical plans service minimum eligibility age                 55 years    
Minimum | International Pension Benefits | Cash and Cash Equivalents [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum (Deprecated 2017-01-31) 1.00%       1.00%       1.00% 1.00%  
Minimum | Employee Defined Contribution Plans [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined contribution plan, employer contribution (percentage)                 3.00%    
Minimum | Amended Employee Defined Contribution Plans                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined contribution plan, employer contribution (percentage)                 5.00%    
Maximum                      
Defined Benefit Plan Disclosure [Line Items]                      
Duration for unfunded commitments to be contributed 6 years               6 years    
Maximum | Private Equity and Real Estate | Other Investments [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Redemption notice period, upper limit                 15 years    
Maximum | International Pension Benefits | Cash and Cash Equivalents [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum (Deprecated 2017-01-31) 10.00%       10.00%       10.00% 10.00%  
Maximum | Employee Defined Contribution Plans [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined contribution plan, employer contribution (percentage)                 8.00%    
Maximum | Amended Employee Defined Contribution Plans                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined contribution plan, employer contribution (percentage)                 8.00%    
Defined Benefit Plan, Actuarial Assumptions Discount Rate                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined benefit plan net actuarial loss                 $ (7,300,000,000) $ (7,500,000,000)  
Defined Benefit Plan, Actuarial Assumptions Demographic and Assumption Changes [Member]                      
Defined Benefit Plan Disclosure [Line Items]                      
Defined benefit plan net actuarial loss                 $ (513,000,000) $ 40,000,000