POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Liability for Unpaid Claims and Claims Expenses
Net balance, beginning of period			$ 5,187
Less claims paid during the period on claims incurred during:
Net balance, end of period	$ 4,921		4,921
Total liability for unpaid policy claims	4,921	$ 4,773	4,921	$ 4,773
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of period	4,192	3,983	4,389	3,968
Less reinsurance recoverables	37	33	39	31
Net balance, beginning of period	4,155	3,950	4,350	3,937
Add claims incurred during the period related to:
Current year	1,710	1,736	3,570	3,574
Prior years	(198)	(166)	(518)	(302)
Total incurred	1,512	1,570	3,052	3,272
Less claims paid during the period on claims incurred during:
Current year	1,139	1,127	1,657	1,681
Prior years	407	411	1,461	1,558
Total paid	1,546	1,538	3,118	3,239
Effect of foreign exchange rate changes on unpaid claims	4	22	(159)	34
Net balance, end of period	4,125	4,004	4,125	4,004
Add reinsurance recoverables	37	37	37	37
Total liability for unpaid policy claims	4,162	4,041	4,162	4,041
Life insurance
Less claims paid during the period on claims incurred during:
Total liability for unpaid policy claims	$ 759	$ 732	$ 759	$ 732