POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 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	$ 4,909		4,909
Total liability for unpaid policy claims	4,909	$ 4,976	4,909	$ 4,976
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of period	4,162	4,041	4,389	3,968
Less reinsurance recoverables	37	37	39	31
Net balance, beginning of period	4,125	4,004	4,350	3,937
Add claims incurred during the period related to:
Current year	1,720	1,780	5,302	5,354
Prior years	(215)	(105)	(739)	(408)
Total incurred	1,505	1,675	4,563	4,946
Less claims paid during the period on claims incurred during:
Current year	1,279	1,295	2,947	2,971
Prior years	219	249	1,676	1,811
Total paid	1,498	1,544	4,623	4,782
Effect of foreign exchange rate changes on unpaid claims	(29)	42	(187)	76
Net balance, end of period	4,103	4,177	4,103	4,177
Add reinsurance recoverables	39	40	39	40
Total liability for unpaid policy claims	4,142	4,217	4,142	4,217
Life insurance
Less claims paid during the period on claims incurred during:
Total liability for unpaid policy claims	$ 767	$ 759	$ 767	$ 759