CAPITALIZATION - Long-term Debt and Other Long-term Obligations (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Schedule of Capitalization [Line Items]
Finance leases	$ 36	$ 45
Unamortized debt discounts	(8)	(34)
Unamortized debt issuance costs	(126)	(118)
Unamortized fair value adjustments	6	7
Currently payable long-term debt	(1,606)	(146)
Total long-term debt and other long-term obligations	22,248	22,131
FMBs and secured notes - fixed rate
Schedule of Capitalization [Line Items]
FMBs and secured notes - fixed rate	$ 5,021	4,802
FMBs and secured notes - fixed rate \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	2.65%
FMBs and secured notes - fixed rate \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	8.25%
Unsecured notes - fixed rate
Schedule of Capitalization [Line Items]
Unsecured notes - fixed rate	$ 18,925	$ 17,575
Unsecured notes - fixed rate \| Minimum
Schedule of Capitalization [Line Items]
Interest rate (percent)	1.60%
Unsecured notes - fixed rate \| Maximum
Schedule of Capitalization [Line Items]
Interest rate (percent)	7.375%

Debt Instrument, Unamortized Merger Fair Value Adjustments

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Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after accumulated amortization, of debt discount (premium).

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- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Present value of lessee's discounted obligation for lease payments from finance lease.

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Amount of long-term debt and lease obligation, classified as noncurrent.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount of long-term debt classified as other.

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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.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of uncollateralized debt obligations (with maturities initially due after one year or beyond the operating cycle if longer).

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