INCOME TAXES - Net Deferred Income Taxes and Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Uncertainties [Abstract]
Tax Reform Act, income tax benefit for reduction of deferred taxes		$ 1,331
Tax Cuts and Jobs Act of 2017, deferred tax asset revaluation due to sequestration fee, income tax expense		20
Tax Cuts and Jobs Act of 2017, transition tax		23
Interest and penalties included in unrecognized tax benefits		23	$ 67
Interest expense related to unrecognized tax benefits		(44)	(15)	$ (25)
Components of Deferred Tax Assets [Abstract]
Compensation and related benefits		47	88
Net operating loss		0	0
Reserves and reinsurance		0
Alternative minimum tax credits		387	394
Other		67	5
Total		501	487
Components of Deferred Tax Liabilities [Abstract]
Reserves and reinsurance		83	534
DAC		821	1,463
Unrealized investment gains (losses)		298	23
Investments		997	1,062
Other		0	0
Total		2,199	3,082
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1,		457	418	475
Additions for tax positions of prior years	$ 221	28	39	44
Reductions for tax positions of prior years		(245)	0	(101)
Additions for tax positions of current year		0	0	0
Settlements with Tax Authorities		(33)	0	0
Balance at December 31,		207	457	418
Unrecognized tax benefits that, if recognized, would impact the effective rate		$ 172	$ 329	$ 293