SCHEDULE III SUPPLEMENTARY INSURANCE INFORMATION - (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	$ 9,525	$ 10,441
Future policy benefits & unpaid policy claims	95,424	102,970
Unearned premiums	2,576	3,597
Other policyholders' funds	7,072	7,824
Net premium income	17,647	18,622	$ 18,780
Net investment income	3,818	3,638	3,578
Benefits and claims, net	10,576	11,796	11,942
Amortization of deferred policy acquisition costs	1,170	1,214	1,282
Other operating expenses	5,038	4,978	4,638
Premiums written	17,137	18,075	18,180
Intercompany eliminations
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	0	0
Future policy benefits & unpaid policy claims	(733)	(821)
Unearned premiums	0	0
Other policyholders' funds	0	0
Aflac Japan
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	6,233	6,991	6,584
Future policy benefits & unpaid policy claims	84,079	91,829
Unearned premiums	2,469	3,488
Other policyholders' funds	7,064	7,811
Net premium income	11,853	12,670	12,772
Net investment income	3,139	2,856	2,753
Benefits and claims, net	7,963	8,851	8,877
Amortization of deferred policy acquisition costs	653	644	709
Other operating expenses	2,555	2,613	2,465
Premiums written	11,600	12,312	12,367
Aflac U.S.
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	3,292	3,450	3,544
Future policy benefits & unpaid policy claims	11,798	11,684
Unearned premiums	111	113
Other policyholders' funds	8	13
Net premium income	5,614	5,758	5,808
Net investment income	752	702	720
Benefits and claims, net	2,447	2,765	2,871
Amortization of deferred policy acquisition costs	517	570	573
Other operating expenses	2,048	1,963	1,834
Premiums written	5,537	5,763	5,813
All other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Deferred policy acquisition costs	0	0
Future policy benefits & unpaid policy claims	280	278
Unearned premiums	(4)	(4)
Other policyholders' funds	0	0
Net premium income	180	194	200
Net investment income	(73)	80	105
Benefits and claims, net	166	180	194
Amortization of deferred policy acquisition costs	0	0	0
Other operating expenses	435	402	339
Premiums written	$ 0	$ 0	$ 0