Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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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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The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

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Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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FAIR VALUE MEASUREMENTS (Additional Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	$ 0	$ 0
Noncash settlement transactions	23
Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at Jan 1	677	1,237
Gain (loss) included in earnings	3	(8)
Purchases	0	8,910
Settlements	(680)	(9,462)
Balance at Dec 31	0	677
Fair Value, Measurements, Nonrecurring \| Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets at fair value:		$ 61	$ 0
Fair Value, Measurements, Nonrecurring \| Private Market Securities and Real Estate \| Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unfunded commitments on investments	89
Fair Value, Measurements, Nonrecurring \| Private Market Securities \| Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets at fair value:	120
Fair Value, Measurements, Nonrecurring \| Real Estate \| Fair Value Measured at Net Asset Value Per Share
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Assets at fair value:	$ 29