FAIR VALUE DISCLOSURES - TEXTUAL (Details)	9 Months Ended		12 Months Ended
	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2018 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Quantitative Disclosure [Line Items]
Fixed maturities, available-for-sale			$ 36,515,000,000	$ 39,754,000,000
Fair value adjustments on GMIB asset	$ 107,000,000		69,000,000
Transfers out of Level 3	28,000,000	$ 7,000,000
Transfers into level 3	$ 65,000,000	$ 6,000,000
Transfers out of Levels 2 and 3 to total equity (as a percent)	0.60%	0.10%
Investments which the underlying quantitative inputs are not developed by the Company and are not readily available			395,000,000	$ 964,000,000
Level 3 | Corporate | Matrix pricing model
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Quantitative Disclosure [Line Items]
Fair value of privately placed, available-for-sale corporate debt securities classified as Level 3	$ 39,000,000		53,000,000
Level 3 | Separate Accounts Assets | Third party appraisal
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Quantitative Disclosure [Line Items]
Fair value of privately placed, available-for-sale corporate debt securities classified as Level 3	345,000,000		326,000,000
Alliance Bernstein | Level 3 | AB 2016 Acquisition
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Quantitative Disclosure [Line Items]
Acquisition-related contingent consideration liability	$ 11,000,000		$ 11,000,000
Long-term revenue growth rate | Alliance Bernstein | Level 3 | AB 2016 Acquisition
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Quantitative Disclosure [Line Items]
Acquisition-related contingent consideration liability, measurement input	0.310		0.310
Discount rate | Alliance Bernstein | Level 3 | AB 2016 Acquisition | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Quantitative Disclosure [Line Items]
Acquisition-related contingent consideration liability, measurement input	0.014		0.014
Discount rate | Alliance Bernstein | Level 3 | AB 2016 Acquisition | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Quantitative Disclosure [Line Items]
Acquisition-related contingent consideration liability, measurement input	0.023		0.023