INCOME TAXES - Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax expense	$ 460	$ 462	$ 260
Tax effect of changes in OCI	225	(96)	(7)
Total comprehensive income tax expense	$ 685	$ 366	$ 253