DEBT AND FINANCING COSTS - Schedule of Debt (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt	$ 7,937	$ 7,934
Unsecured Debt
Debt Instrument [Line Items]
Debt before unamortized discount and deferred loan costs	8,430	8,580
Unamortized discount	(46)	(47)
Deferred loan costs	(47)	(49)
Total debt	8,337	8,484
Current maturities	(400)	(550)
Long-term debt	$ 7,937	$ 7,934

Face (par) amount of debt instrument at time of issuance.

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

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

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