INVESTMENTS - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019 USD ($) investment	Sep. 30, 2018 investment	Sep. 30, 2019 USD ($) investment	Sep. 30, 2018 investment	Dec. 31, 2018 USD ($)
Schedule of Investments [Line Items]
Held to maturity securities transferred to available for sale securities, number of investments | investment	0	0	0	0
Equity securities, FV-NI, unrealized gain (loss)	$ 21		$ 38
Transitional real estate loan commitments	1,300		1,300
Commercial mortgage loan commitments	293		293
Middle market loan program unfunded amount	36		36		$ 56
Middle market loan commitments	447		447
Limited partnerships investment commitments	$ 1,700		1,700
Specific loan loss reserves			$ 2		$ 0
Percentage that the lending policy requires that the fair value of the securities received as collateral be of the fair value of the loaned securities	102.00%		102.00%
Percentage that the lending policy requires that the fair value of the unrestricted cash received as collateral be of the fair value of the loaned securities	100.00%		100.00%