FAIR VALUE MEASUREMENTS (Schedule of Maturities on Debt Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Total maturities of fixed-income securities	$ 3,372	$ 3,303
Fixed-income securities
Debt Securities, Available-for-sale [Line Items]
Less than 1 year	69
1–5 years	401
5–10 years	386
More than 10 years	513
Total maturities of fixed-income securities	$ 1,369	$ 1,295

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