INCOME TAXES - Principal Components of Net Deferred Tax Balances (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Compensation and other accrued expense	$ 171	$ 111
Benefits payable	87	89
Net operating loss carryforward	32	42
Deferred acquisition costs	26	22
Unearned revenues	12	8
Other	11	8
Capital loss carryforward	0	1
Total deferred income tax assets	339	281
Valuation allowance	(37)	(45)
Total deferred income tax assets, net of valuation allowance	302	236
Depreciable property and intangible assets	(449)	(329)
Investment securities	(418)	(181)
Prepaid expenses	(91)	(64)
Future policy benefits payable	(3)	(3)
Total deferred income tax liabilities	(961)	(577)
Total net deferred income tax liabilities	$ (659)	$ (341)