INSURANCE LIABILITIES - INVESTMENT IN VARIABLE INSURANCE TRUST MUTUAL FUNDS (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
GMDB
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	$ 95,299	$ 94,672
GMDB | Equity
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	42,675	41,658
GMDB | Fixed income
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	5,274	5,469
GMDB | Balanced
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	46,504	46,577
GMDB | Other
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	846	968
GMDB | As Previously Reported | Equity
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		78,069
GMDB | As Previously Reported | Fixed income
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		2,234
GMDB | As Previously Reported | Balanced
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		14,084
GMDB | As Previously Reported | Other
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		283
GMIB
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	61,278	62,286
GMIB | Equity
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	19,512	19,928
GMIB | Fixed income
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	2,924	3,150
GMIB | Balanced
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	38,540	38,890
GMIB | Other
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds	$ 302	318
GMIB | As Previously Reported | Equity
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		50,429
GMIB | As Previously Reported | Fixed income
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		1,568
GMIB | As Previously Reported | Balanced
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		10,165
GMIB | As Previously Reported | Other
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Investment in Variable Insurance Trust Mutual Funds		$ 124