INVESTMENTS - TRADING SECURITIES (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Debt Securities, Trading, Gain (Loss) [Abstract]
Net investment gains (losses) recognized during the period on securities held at the end of the period	$ (20)	$ 45	$ (192)	$ 153
Net investment gains (losses) recognized on securities sold during the period	(5)	10	(14)	35
Unrealized and realized gains (losses) on trading securities arising during the period	(25)	55	(206)	188
Interest and dividend income from trading securities	82	54	228	143
Net investment income (loss) from trading securities	$ 57	$ 109	$ 22	$ 331