POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 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	$ 4,773		4,773
Total liability for unpaid policy claims	4,773	$ 4,706	4,773	$ 4,706
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of period	3,983	3,967	3,968	3,952
Less reinsurance recoverables	33	29	31	28
Net balance, beginning of period	3,950	3,938	3,937	3,924
Add claims incurred during the period related to:
Current year	1,736	1,785	3,574	3,610
Prior years	(166)	(136)	(302)	(303)
Total incurred	1,570	1,649	3,272	3,307
Less claims paid during the period on claims incurred during:
Current year	1,127	1,229	1,681	1,735
Prior years	411	430	1,558	1,568
Total paid	1,538	1,659	3,239	3,303
Effect of foreign exchange rate changes on unpaid claims	22	65	34	65
Net balance, end of period	4,004	3,993	4,004	3,993
Add reinsurance recoverables	37	31	37	31
Total liability for unpaid policy claims	4,041	4,024	4,041	4,024
Life insurance
Less claims paid during the period on claims incurred during:
Total liability for unpaid policy claims	$ 732	$ 682	$ 732	$ 682