DERIVATIVES - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Cash and securities collateral for derivative contract	$ 3,800	$ 3,000
Cash and securities collateral	29	74
S&P 500, Russell 1000, NASDAQ 100 and Emerging Market Indices
Derivative [Line Items]
Initial margin requirement	466	252
Us Treasury Notes Ultra Long Bonds And Euro Dollar
Derivative [Line Items]
Initial margin requirement	651	166
Euro Stoxx, FTSE100, EAFE And Topix Indices
Derivative [Line Items]
Initial margin requirement	$ 159	$ 60