Schedule II - Aflac Incorporated (Parent Only) - Condensed Statements of Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Financial Statements, Captions [Line Items]
Net earnings	$ 4,659	$ 4,418	$ 4,231
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period	(366)	(1,034)	(861)
Unrealized holding gains (losses) on fixed maturity securities during period	2,493	(12,603)	(929)
Unrealized gains (losses) on derivatives during period	6	4	5
Effect of changes in discount rate assumptions during period	(582)	17,384	3,466
Pension liability adjustment during period	35	165	148
Total other comprehensive income (loss) before income taxes	1,420	3,463	1,798
Income tax expense (benefit) related to items of other comprehensive income (loss)	511	1,481	573
Other comprehensive income (loss), net of tax	909	1,982	1,225
Total comprehensive income (loss)	5,568	6,400	5,456
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net earnings	4,659	4,418	4,231
Other comprehensive income (loss) before income taxes:
Unrealized foreign currency translation gains (losses) during period	(366)	(1,034)	(861)
Unrealized holding gains (losses) on fixed maturity securities during period	2,327	(13,056)	(960)
Unrealized gains (losses) on derivatives during period	6	4	5
Effect of changes in discount rate assumptions during period	(582)	17,384	3,466
Pension liability adjustment during period	35	165	148
Total other comprehensive income (loss) before income taxes	1,420	3,463	1,798
Income tax expense (benefit) related to items of other comprehensive income (loss)	511	1,481	573
Other comprehensive income (loss), net of tax	909	1,982	1,225
Total comprehensive income (loss)	$ 5,568	$ 6,400	$ 5,456