EMPLOYEE RETIREMENT PLANS - Qualified Defined-benefit Pension Plan Assets at Fair Value by Level within the Fair Value Hierarchy (Details) - Qualified - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value
Private equity funds	$ 99	$ 863	$ 780
Valued at NAV	0	87
Level 1
Fair Value
Private equity funds	46	43
Level 2
Fair Value
Private equity funds	47	732
Level 3
Fair Value
Private equity funds	6	1
United States | Common and Preferred Stocks:
Fair Value
Private equity funds	25	113
Valued at NAV	0	87
United States | Corporate Debt Securities:
Fair Value
Private equity funds	5	143
Valued at NAV	0	0
United States | Government and Other Debt Securities:
Fair Value
Private equity funds	4	214
Valued at NAV	0	0
United States | Real Estate
Fair Value
Private equity funds	3
Valued at NAV	0
United States | Common Collective Trust Fund – United States
Fair Value
Private equity funds		292
Valued at NAV		0
United States | Level 1 | Common and Preferred Stocks:
Fair Value
Private equity funds	25	26
United States | Level 1 | Corporate Debt Securities:
Fair Value
Private equity funds	0	0
United States | Level 1 | Government and Other Debt Securities:
Fair Value
Private equity funds	0	0
United States | Level 1 | Real Estate
Fair Value
Private equity funds	3
United States | Level 1 | Common Collective Trust Fund – United States
Fair Value
Private equity funds		0
United States | Level 2 | Common and Preferred Stocks:
Fair Value
Private equity funds	0	0
United States | Level 2 | Corporate Debt Securities:
Fair Value
Private equity funds	5	143
United States | Level 2 | Government and Other Debt Securities:
Fair Value
Private equity funds	4	214
United States | Level 2 | Real Estate
Fair Value
Private equity funds	0
United States | Level 2 | Common Collective Trust Fund – United States
Fair Value
Private equity funds		292
United States | Level 3 | Common and Preferred Stocks:
Fair Value
Private equity funds	0	0
United States | Level 3 | Corporate Debt Securities:
Fair Value
Private equity funds	0	0
United States | Level 3 | Government and Other Debt Securities:
Fair Value
Private equity funds	0	0
United States | Level 3 | Real Estate
Fair Value
Private equity funds	0
United States | Level 3 | Common Collective Trust Fund – United States
Fair Value
Private equity funds		0
International | Common and Preferred Stocks:
Fair Value
Private equity funds	13	15
Valued at NAV	0	0
International | Private Equity and Hedge Funds – International
Fair Value
Private equity funds		1
Valued at NAV		0
International | Corporate Debt Securities:
Fair Value
Private equity funds	2	23
Valued at NAV	0	0
International | Government and Other Debt Securities:
Fair Value
Private equity funds	36	46
Valued at NAV	0	0
International | Real Estate
Fair Value
Private equity funds	8
Valued at NAV	0
International | Buy-in Annuity - International
Fair Value
Private equity funds		14
Valued at NAV		0
International | Short-Term and Other Investments – International
Fair Value
Private equity funds	3	2
Valued at NAV	0	0
International | Level 1 | Common and Preferred Stocks:
Fair Value
Private equity funds	13	15
International | Level 1 | Private Equity and Hedge Funds – International
Fair Value
Private equity funds		0
International | Level 1 | Corporate Debt Securities:
Fair Value
Private equity funds	0	0
International | Level 1 | Government and Other Debt Securities:
Fair Value
Private equity funds	0	0
International | Level 1 | Real Estate
Fair Value
Private equity funds	2
International | Level 1 | Buy-in Annuity - International
Fair Value
Private equity funds		0
International | Level 1 | Short-Term and Other Investments – International
Fair Value
Private equity funds	3	2
International | Level 2 | Common and Preferred Stocks:
Fair Value
Private equity funds	0	0
International | Level 2 | Private Equity and Hedge Funds – International
Fair Value
Private equity funds		0
International | Level 2 | Corporate Debt Securities:
Fair Value
Private equity funds	2	23
International | Level 2 | Government and Other Debt Securities:
Fair Value
Private equity funds	36	46
International | Level 2 | Real Estate
Fair Value
Private equity funds	0
International | Level 2 | Buy-in Annuity - International
Fair Value
Private equity funds		14
International | Level 2 | Short-Term and Other Investments – International
Fair Value
Private equity funds	0	0
International | Level 3 | Common and Preferred Stocks:
Fair Value
Private equity funds	0	0
International | Level 3 | Private Equity and Hedge Funds – International
Fair Value
Private equity funds		1
International | Level 3 | Corporate Debt Securities:
Fair Value
Private equity funds	0	0
International | Level 3 | Government and Other Debt Securities:
Fair Value
Private equity funds	0	0
International | Level 3 | Real Estate
Fair Value
Private equity funds	6
International | Level 3 | Buy-in Annuity - International
Fair Value
Private equity funds		0
International | Level 3 | Short-Term and Other Investments – International
Fair Value
Private equity funds	$ 0	$ 0