INVESTMENTS - Net Investment Income (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net Investment Income [Line Items]
Investment income	$ 3,442	$ 2,549	$ 2,506
Investment expenses	(144)	(71)	(65)
Net investment income (loss)	3,298	2,478	2,441
Fixed maturities
Net Investment Income [Line Items]
Investment income	1,902	1,540	1,365
Mortgage loans on real estate
Net Investment Income [Line Items]
Investment income	540	494	453
Real estate held for the production of income
Net Investment Income [Line Items]
Investment income	(2)	(6)	2
Other equity investments
Net Investment Income [Line Items]
Investment income	74	123	169
Policy loans
Net Investment Income [Line Items]
Investment income	198	201	205
Trading securities
Net Investment Income [Line Items]
Investment income	712	128	258
Other investment income
Net Investment Income [Line Items]
Investment income	$ 18	$ 69	$ 54

Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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