POLICY LIABILITIES - Changes in Liability for Unpaid Policy Claims (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	$ 5,187	$ 4,659
Net balance, beginning of year	5,187
Less claims paid during the year on claims incurred during:
Net balance, end of year	4,836	5,187
Total liability for unpaid policy claims	4,836	5,187	$ 4,659
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	99	0
Health insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	4,389	3,968	3,952
Less reinsurance recoverables	39	30	27
Net balance, beginning of year	4,350	3,938	3,925
Add claims incurred during the year related to:
Current year	6,969	7,179	7,216
Prior years	(860)	(540)	(552)
Total incurred	6,109	6,639	6,664
Less claims paid during the year on claims incurred during:
Current year	4,356	4,488	4,715
Prior years	1,827	1,966	1,965
Total paid	6,183	6,454	6,680
Effect of foreign exchange rate changes on unpaid claims	(246)	128	29
Net balance, end of year	4,030	4,350	3,938
Add reinsurance recoverables	37	39	30
Total liability for unpaid policy claims	4,067	4,389	3,968
Life insurance
Liability for Unpaid Claims and Claims Expenses
Unpaid supplemental health claims, beginning of year	798	691
Less claims paid during the year on claims incurred during:
Total liability for unpaid policy claims	$ 769	$ 798	$ 691