POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	$ 4,836	$ 5,187
Net balance, beginning of year	4,836
Less claims paid during the year on claims incurred during:
Net balance, end of year	4,561	4,836
Total liability for unpaid policy claims	4,561	4,836	$ 5,187
Zurich North America's U.S. Corporate Life and Pensions business
Less claims paid during the year on claims incurred during:
Liability for Unpaid Claims and Claims Adjustment Expense, Business Acquisitions	0	0	99
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	4,067	4,389	3,968
Less reinsurance recoverables	37	39	30
Net balance, beginning of year	4,030	4,350	3,938
Add claims incurred during the year related to:
Current year	6,412	6,969	7,179
Prior years	(633)	(860)	(540)
Total incurred	5,779	6,109	6,639
Less claims paid during the year on claims incurred during:
Current year	3,973	4,356	4,488
Prior years	1,736	1,827	1,966
Total paid	5,709	6,183	6,454
Effect of foreign exchange rate changes on unpaid claims	(289)	(246)	128
Net balance, end of year	3,811	4,030	4,350
Add reinsurance recoverables	43	37	39
Total liability for unpaid policy claims	3,854	4,067	4,389
Life insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	769	798
Less claims paid during the year on claims incurred during:
Total liability for unpaid policy claims	$ 707	$ 769	$ 798