POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Liability for Unpaid Claims and Claims Expenses
Net balance, beginning of period			$ 4,659
Less claims paid during the period on claims incurred during:
Net balance, end of period	$ 4,976		4,976
Total liability for unpaid policy claims	4,976	$ 4,741	4,976	$ 4,741
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of period	4,041	4,024	3,968	3,952
Less reinsurance recoverables	37	31	31	28
Net balance, beginning of period	4,004	3,993	3,937	3,924
Add claims incurred during the period related to:
Current year	1,780	1,806	5,354	5,415
Prior years	(105)	(134)	(408)	(437)
Total incurred	1,675	1,672	4,946	4,978
Less claims paid during the period on claims incurred during:
Current year	1,295	1,421	2,971	3,150
Prior years	249	220	1,811	1,794
Total paid	1,544	1,641	4,782	4,944
Effect of foreign exchange rate changes on unpaid claims	42	(3)	76	63
Net balance, end of period	4,177	4,021	4,177	4,021
Add reinsurance recoverables	40	31	40	31
Total liability for unpaid policy claims	4,217	4,052	4,217	4,052
Life insurance
Less claims paid during the period on claims incurred during:
Total liability for unpaid policy claims	$ 759	$ 689	$ 759	$ 689