INVESTMENTS - Trading Securities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Investments, Debt and Equity Securities [Abstract]
Net investment gains (losses) recognized during the period on securities held at the end of the period	$ (186)	$ 318
Net investment gains (losses) recognized on securities sold during the period	4	(24)
Unrealized and realized gains (losses) on trading securities	(182)	294
Interest and dividend income from trading securities	51	92
Net investment income (loss) from trading securities	$ (131)	$ 386