DAC AND POLICYHOLDER BONUS INTEREST CREDITS - CONTRACTHOLDER BONUS INTEREST CREDITS (CHANGES IN DEFERRED ACQUISITION COSTS) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Balance, beginning of year	$ 5,058	$ 5,088
Capitalization of commissions, sales and issue expenses	578	594
Amortization	(846)	(646)
Change in unrealized investment gains (losses)	(243)	22
Balance, End of Year	$ 4,547	$ 5,058

Amount of expense related to deferred policy acquisition costs.

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Amount of unrealized investment gain (loss) which decreases (increases) deferred policy acquisition cost.

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Net amount of deferred policy acquisition costs capitalized on contracts remaining in force as of the balance sheet date.

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Total amount of policy acquisition costs capitalized during the income statement period.

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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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