POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	$ 4,045	$ 3,802
Net balance, beginning of year	4,045
Less claims paid during the year on claims incurred during:
Net balance, end of year	4,392	4,045
Total liability for unpaid policy claims	4,392	4,045	$ 3,802
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	3,707	3,548	3,412
Less reinsurance recoverables	27	26	7
Net balance, beginning of year	3,680	3,522	3,405
Add claims incurred during the year related to:
Current year	6,979	7,037	6,416
Prior years	(518)	(465)	(353)
Total incurred	6,461	6,572	6,063
Less claims paid during the year on claims incurred during:
Current year	4,530	4,613	4,227
Prior years	1,822	1,865	1,718
Total paid	6,352	6,478	5,945
Effect of foreign exchange rate changes on unpaid claims	65	64	(1)
Net balance, end of year	3,854	3,680	3,522
Add reinsurance recoverables	30	27	26
Total liability for unpaid policy claims	3,884	3,707	3,548
Life insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	338	254
Less claims paid during the year on claims incurred during:
Total liability for unpaid policy claims	$ 508	$ 338	$ 254