Schedule II - Aflac Incorporated (Parent Only) - Condensed Balance Sheet (Detail 2) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Condensed Financial Statements, Captions [Line Items]
Available for sale, fixed maturity securities, allowance for credit losses	$ 0	$ 0	$ 0	$ 0
Fixed maturity securities, available-for-sale, amortized cost	$ 64,089	$ 70,689
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	1,900,000	1,900,000
Common stock, shares issued (in shares)	1,356,763	1,355,398	1,354,079	1,352,739
Parent Company
Condensed Financial Statements, Captions [Line Items]
Available for sale, fixed maturity securities, allowance for credit losses	$ 0	$ 0
Fixed maturity securities, available-for-sale, amortized cost	$ 1,702	$ 1,447
Common stock, par value (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	1,900,000	1,900,000
Common stock, shares issued (in shares)	1,356,763	1,355,398