FAIR VALUE OF FINANCIAL INSTRUMENTS - Valuation of Level 3 Financial Instruments (Details)	Sep. 30, 2021 USD ($) usd_per_policy	Dec. 31, 2020 USD ($) usd_per_policy
Liabilities
Fair Value	$ 2,576,000,000	$ 3,119,000,000
Level 3 | Commercial mortgage-backed securities
Assets:
Fair value	31,000,000	32,000,000
Level 3 | Other asset-backed securities
Assets:
Fair value	458,000,000	435,000,000
Level 3 | Corporate securities
Assets:
Fair value	1,635,000,000	1,432,000,000
Level 3 | Embedded derivative - GLWB
Assets:
Fair value	535,000,000
Liabilities
Fair Value		822,000,000
Level 3 | Embedded derivative - FIA
Liabilities
Fair Value	570,000,000	573,000,000
Level 3 | Embedded derivative - IUL
Liabilities
Fair Value	$ 251,000,000	$ 201,000,000
Level 3 | Discounted cash flow | Commercial mortgage-backed securities | Minimum
Liabilities
Debt securities, measurement input	0.0212	0.0278
Level 3 | Discounted cash flow | Commercial mortgage-backed securities | Maximum
Liabilities
Debt securities, measurement input	0.0229	0.0292
Level 3 | Discounted cash flow | Commercial mortgage-backed securities | Weighted Average
Liabilities
Debt securities, measurement input	0.0223	0.0287
Level 3 | Discounted cash flow | Corporate securities | Minimum
Liabilities
Debt securities, measurement input	0.0000	0.0000
Level 3 | Discounted cash flow | Corporate securities | Maximum
Liabilities
Debt securities, measurement input	0.0400	0.0475
Level 3 | Discounted cash flow | Corporate securities | Weighted Average
Liabilities
Debt securities, measurement input	0.0146	0.0189
Level 3 | Actuarial cash flow model | Embedded derivative - FIA
Liabilities
Embedded derivative, measurement input | usd_per_policy	214	207
Liquidation value | Level 3 | Liquidation | Other asset-backed securities | Minimum
Liabilities
Debt securities, measurement input, value	$ 97.00	$ 95
Liquidation value | Level 3 | Liquidation | Other asset-backed securities | Maximum
Liabilities
Debt securities, measurement input, value	99.75	97
Liquidation value | Level 3 | Liquidation | Other asset-backed securities | Weighted Average
Liabilities
Debt securities, measurement input, value	$ 98.77	$ 96.19
Liquidity premium | Level 3 | Discounted cash flow | Minimum
Liabilities
Debt securities, measurement input		0.0054
Liquidity premium | Level 3 | Discounted cash flow | Maximum
Liabilities
Debt securities, measurement input		0.023
Liquidity premium | Level 3 | Discounted cash flow | Weighted Average
Liabilities
Debt securities, measurement input		0.0163
Liquidity premium | Level 3 | Discounted cash flow | Other asset-backed securities | Minimum
Liabilities
Debt securities, measurement input	0.0084
Liquidity premium | Level 3 | Discounted cash flow | Other asset-backed securities | Maximum
Liabilities
Debt securities, measurement input	0.0231
Liquidity premium | Level 3 | Discounted cash flow | Other asset-backed securities | Weighted Average
Liabilities
Debt securities, measurement input	0.0176
Paydown rate | Level 3 | Discounted cash flow | Other asset-backed securities | Minimum
Liabilities
Debt securities, measurement input	0.1003	0.0879
Paydown rate | Level 3 | Discounted cash flow | Other asset-backed securities | Maximum
Liabilities
Debt securities, measurement input	0.1315	0.1249
Paydown rate | Level 3 | Discounted cash flow | Other asset-backed securities | Weighted Average
Liabilities
Debt securities, measurement input	0.1195	0.1139
Mortality rate | Level 3 | Actuarial cash flow model | Embedded derivative - GLWB | Minimum
Liabilities
Embedded derivative, measurement input	0.88	0.88
Mortality rate | Level 3 | Actuarial cash flow model | Embedded derivative - GLWB | Maximum
Liabilities
Embedded derivative, measurement input	1	1
Mortality rate | Level 3 | Actuarial cash flow model | Embedded derivative - FIA | Minimum
Liabilities
Embedded derivative, measurement input	0.88	0.88
Mortality rate | Level 3 | Actuarial cash flow model | Embedded derivative - FIA | Maximum
Liabilities
Embedded derivative, measurement input	1	1
Mortality rate | Level 3 | Actuarial cash flow model | Embedded derivative - IUL | Minimum
Liabilities
Embedded derivative, measurement input	0.43	0.36
Mortality rate | Level 3 | Actuarial cash flow model | Embedded derivative - IUL | Maximum
Liabilities
Embedded derivative, measurement input	1.10	1.61
Mortality rate | Level 3 | Actuarial cash flow model, valuation basic report primary tables based on duration scale | Embedded derivative - IUL | Minimum
Liabilities
Embedded derivative, measurement input	0.94	0.94
Mortality rate | Level 3 | Actuarial cash flow model, valuation basic report primary tables based on duration scale | Embedded derivative - IUL | Maximum
Liabilities
Embedded derivative, measurement input	2.48	2.48
Nonperformance risk | Level 3 | Actuarial cash flow model | Embedded derivative - GLWB | Minimum
Liabilities
Embedded derivative, measurement input	0.0018	0.0019
Nonperformance risk | Level 3 | Actuarial cash flow model | Embedded derivative - GLWB | Maximum
Liabilities
Embedded derivative, measurement input	0.0081	0.0081
Nonperformance risk | Level 3 | Actuarial cash flow model | Embedded derivative - FIA | Minimum
Liabilities
Embedded derivative, measurement input	0.0018	0.0019
Nonperformance risk | Level 3 | Actuarial cash flow model | Embedded derivative - FIA | Maximum
Liabilities
Embedded derivative, measurement input	0.0081	0.0081
Nonperformance risk | Level 3 | Actuarial cash flow model | Embedded derivative - IUL | Minimum
Liabilities
Embedded derivative, measurement input	0.0018	0.0019
Nonperformance risk | Level 3 | Actuarial cash flow model | Embedded derivative - IUL | Maximum
Liabilities
Embedded derivative, measurement input	0.0081	0.0081
Withdrawal rate prior to age 70 | Level 3 | Actuarial cash flow model | Embedded derivative - FIA
Liabilities
Embedded derivative, measurement input	0.004	0.004
Withdrawal rate for ages over 70 | Level 3 | Actuarial cash flow model | Embedded derivative - FIA
Liabilities
Embedded derivative, measurement input	0.024	0.024
Lapse rate | Level 3 | Actuarial cash flow model | Embedded derivative - FIA | Minimum
Liabilities
Embedded derivative, measurement input	0.002	0.002
Lapse rate | Level 3 | Actuarial cash flow model | Embedded derivative - FIA | Maximum
Liabilities
Embedded derivative, measurement input	0.500	0.500
Lapse rate | Level 3 | Actuarial cash flow model | Embedded derivative - IUL | Minimum
Liabilities
Embedded derivative, measurement input	0.00375	0.00375
Lapse rate | Level 3 | Actuarial cash flow model | Embedded derivative - IUL | Maximum
Liabilities
Embedded derivative, measurement input	0.075	0.10