COMPANY-SPONSORED EMPLOYEE BENEFIT PLANS - Additional Information (Detail)		3 Months Ended		12 Months Ended
	Apr. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2019 USD ($) Employee	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($) Employee
Defined Benefit Plan Disclosure [Line Items]
Number of covered persons | Employee			18,800			18,800
Lump Sum Pension Payments			$ 820,000,000
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)	$ 2,100,000,000			$ (6,500,000,000)	$ (10,100,000,000)
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit	$ 3,700,000,000
Defined Benefit Plan, Increase In Discount Rate	0.49%
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Due To Workforce Reduction	$ 100,000,000
Actual return on plan assets	$ 1,700,000,000
Defined Benefit Plan, Percentage Points Below Expected Return	4.30%
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax	$ 2,100,000,000
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), before Tax		$ 69,000,000
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Tax		52,000,000
Other Comprehensive Income (Loss), Defined Benefit Plan, Plan Amendments, Reclassification Adjustment from AOCI, before Tax		66,000,000
Other Comprehensive Income (Loss), Defined Benefit Plan, Plan Amendments, Reclassification Adjustment from AOCI, After Tax		$ 50,000,000
Pension and postretirement benefit (income) expense				$ (2,456,000,000)	7,125,000,000	$ 3,141,000,000
Health care cost trends, initial annual rate increase				6.25%
Health care cost trends, an ultimate trend rate				4.50%
Employer contributions				$ 576,000,000	$ 3,125,000,000	$ 2,362,000,000
Service cost discount rate				3.11%	2.87%	3.55%
Common stock held in plan assets (in shares) | shares				0	0
Private Equity and Real Estate | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Unfunded commitments to limited partnerships				$ 3,000,000,000.0
Defined Benefit Plan, Actuarial Assumptions Discount Rate
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)				(2,400,000,000)	$ (7,300,000,000)
Defined Benefit Plan, Actuarial Assumptions Demographic and Assumption Changes
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)				(973,000,000)	513,000,000
Employee Defined Contribution Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions charged to expense				153,000,000	139,000,000	$ 130,000,000
Pension and postretirement benefit (income) expense				107,000,000	84,000,000	67,000,000
Amended Employee Defined Contribution Plans
Defined Benefit Plan Disclosure [Line Items]
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				112,000,000	107,000,000	$ 97,000,000
UPS/IBT Plan
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Actuarial Gain (Loss), Immediate Recognition as Component in Net Periodic Benefit (Cost) Credit				6,400,000,000
Defined Benefit Plan, Reduction Of Liability For Coordinating Benefits				5,100,000,000
Defined Benefit Plan, Actuarial Gain (Loss), Other Actuarial Assumptions				1,300,000,000
Defined Benefit Plan, Gain (Loss) From Increase In Discount Rate				$ 1,600,000,000
Defined Benefit Plan, Increase (Decrease) In Discount Rate				0.72%
Defined Benefit Plan, Gain (Loss) On Actual Asset Returns				$ 300,000,000
Defined Benefit Plan, Difference In Expected Return, Percent				2.20%
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax				$ 3,100,000,000
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax				3,300,000,000
Reclassification to earnings (net of tax effect of $67, $1,876 and $378)				2,500,000,000
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for pension plans				62,700,000,000	66,900,000,000
Employer contributions				29,000,000	26,000,000
Pension Benefits | Central States, South East & South West Areas Health and Welfare Fund
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss)				(5,100,000,000)	(2,300,000,000)
Multiemployer Plans, Withdrawal Obligation				6,100,000,000
Liability, Defined Benefit Pension Plan					5,500,000,000
Postemployment Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for pension plans				2,600,000,000	2,800,000,000
Postretirement Medical Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions				$ 63,000,000	$ 77,000,000
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Duration for unfunded commitments to be contributed				3 years
Minimum [Member] | Private Equity and Real Estate | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Redemption notice period, lower limit				10 years
Minimum [Member] | Employee Defined Contribution Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer contribution (percentage)				3.00%
Minimum [Member] | Amended Employee Defined Contribution Plans
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer contribution (percentage)				5.00%
Minimum [Member] | 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
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Duration for unfunded commitments to be contributed				6 years
Maximum [Member] | Private Equity and Real Estate | Other Investments
Defined Benefit Plan Disclosure [Line Items]
Redemption notice period, upper limit				15 years
Maximum [Member] | Employee Defined Contribution Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer contribution (percentage)				8.00%
Maximum [Member] | Amended Employee Defined Contribution Plans
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, employer contribution (percentage)				8.00%