Changes in Liability for Policy and Contract Claims (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance	$ 11,486
Ending balance	11,415
Long-term Care Insurance
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Beginning balance	11,486	$ 10,750
Less reinsurance recoverables	(2,431)	(2,406)
Net beginning balance	9,055	8,344
Current year	1,054	1,005
Prior years	(229)	(106)
Total incurred	825	899
Current year	(197)	(128)
Prior years	(725)	(708)
Total paid	(922)	(836)
Interest on liability for policy and contract claims	101	102
Foreign currency translation	0	(2)
Net ending balance	9,059	8,507
Add reinsurance recoverables	2,356	2,441
Ending balance	$ 11,415	$ 10,948