SIGNIFICANT ACCOUNTING POLICIES - Policyholders' Account Balances and Future Policy Benefits and Various Policies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Liability For Future Policy Benefits Assumptions [Line Items]
Percentage of life insurance liabilities calculate within traditional life interest rate range	99.20%
Separate Accounts Disclosure [Abstract]
Gain (loss) recognized on assets transferred to separate account	$ 16,600	$ 22,900	$ (7,200)
Capitalized Computer Software and Hosting Arrangements [Abstract]
Computer software and hosting arrangements	130	126
Amortization of computer software and hosting arrangements	$ 47	$ 36	$ 35
Minimum | Life Insurance Liabilities
Liability For Future Policy Benefits Assumptions [Line Items]
Liability for future policy benefits, interest rate	3.50%
Minimum | Annuity Liabilities
Liability For Future Policy Benefits Assumptions [Line Items]
Liability for policyholder contract deposits, interest rate	1.60%
Maximum | Life Insurance Liabilities
Liability For Future Policy Benefits Assumptions [Line Items]
Liability for future policy benefits, interest rate	6.30%
Maximum | Annuity Liabilities
Liability For Future Policy Benefits Assumptions [Line Items]
Liability for policyholder contract deposits, interest rate	5.50%
Weighted Average | Life Insurance Liabilities
Liability For Future Policy Benefits Assumptions [Line Items]
Liability for future policy benefits, interest rate	5.00%
Weighted Average | Annuity Liabilities
Liability For Future Policy Benefits Assumptions [Line Items]
Liability for policyholder contract deposits, interest rate	4.80%
Computer Software, Intangible Asset | Minimum
Capitalized Computer Software and Hosting Arrangements [Abstract]
Intangible asset useful life	3 years
Computer Software, Intangible Asset | Maximum
Capitalized Computer Software and Hosting Arrangements [Abstract]
Intangible asset useful life	5 years