Schedule II - Aflac Incorporated (Parent Only) - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net earnings		$ 4,659	$ 4,418	$ 4,231
Adjustments to reconcile net earnings to net cash provided from operating activities:
Other, net		1,043	(136)	574
Net cash provided (used) by operating activities		3,190	3,879	5,051
Cash flows from investing activities:
Fixed maturity securities purchased		(2,801)	(3,514)	(5,813)
Other investments sold (purchased)		(417)	(227)	(1,066)
Settlement of derivatives		79	(61)	199
Other, net		(149)	112	41
Net cash provided (used) by investing activities		817	(1,540)	(2,378)
Cash flows from financing activities:
Purchases of treasury stock		(2,801)	(2,401)	(2,301)
Proceeds from borrowings		204	1,277	1,153
Principal payments under debt obligations		0	(1,416)	(700)
Dividends paid to shareholders		(966)	(979)	(855)
Treasury stock reissued		17	17	26
Proceeds from exercise of stock options		16	16	26
Other, net		(17)	34	(26)
Net cash provided (used) by financing activities		(3,723)	(3,551)	(2,739)
Net change in cash and cash equivalents		363	(1,108)	(90)
Cash and cash equivalents, beginning of period		3,943
Cash and cash equivalents, end of period		4,306	3,943
Parent Company
Cash flows from operating activities:
Net earnings		4,659	4,418	4,231
Adjustments to reconcile net earnings to net cash provided from operating activities:
Equity in earnings of subsidiaries	[1]	(4,418)	(4,787)	(4,364)
Cash dividends received from subsidiaries		3,410	2,705	2,791
Other, net		(686)	18	408
Net cash provided (used) by operating activities		2,965	2,354	3,066
Cash flows from investing activities:
Fixed maturity securities sold		547	392	483
Fixed maturity securities purchased		(345)	(438)	(489)
Other investments sold (purchased)		(34)	(206)	(421)
Settlement of derivatives		693	718	135
Additional capitalization of subsidiaries	[1]	(203)	(294)	(161)
Other, net		1	1	1
Net cash provided (used) by investing activities		659	173	(452)
Cash flows from financing activities:
Purchases of treasury stock		(2,801)	(2,401)	(2,301)
Proceeds from borrowings		0	1,277	1,153
Principal payments under debt obligations		0	(1,416)	(700)
Dividends paid to shareholders		(966)	(979)	(855)
Treasury stock reissued		17	17	26
Proceeds from exercise of stock options		13	12	17
Net change in amount due to/from subsidiary	[1]	(6)	16	43
Other, net		(17)	(7)	(26)
Net cash provided (used) by financing activities		(3,760)	(3,481)	(2,643)
Net change in cash and cash equivalents		(136)	(954)	(29)
Cash and cash equivalents, beginning of period		1,143	2,097	2,126
Cash and cash equivalents, end of period		$ 1,007	$ 1,143	$ 2,097

[1] Eliminated in consolidation