Schedule II - Aflac Incorporated (Parent Only) - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net earnings		$ 4,325	$ 4,778	$ 3,304
Adjustments to reconcile net earnings to net cash provided from operating activities:
Other, net		(79)	182	358
Net cash provided (used) by operating activities		5,051	5,958	5,455
Cash flows from investing activities:
Fixed maturity securities purchased		(5,813)	(4,772)	(6,934)
Other investments sold (purchased)		(1,066)	(860)	(653)
Settlement of derivatives		199	18	(9)
Other, net		41	(265)	(123)
Net cash provided (used) by investing activities		(2,378)	(4,619)	(3,171)
Cash flows from financing activities:
Purchases of treasury stock		(2,301)	(1,537)	(1,627)
Proceeds from borrowings		1,153	1,545	615
Principal payments under debt obligations		(700)	(350)	0
Dividends paid to shareholders		(855)	(769)	(771)
Treasury stock reissued		26	34	49
Proceeds from exercise of stock options		26	18	40
Other, net		(26)	(27)	22
Net cash provided (used) by financing activities		(2,739)	(1,115)	(1,713)
Net change in cash and cash equivalents		(90)	245	559
Cash and cash equivalents, beginning of period		5,141
Cash and cash equivalents, end of period		5,051	5,141
Parent Company
Cash flows from operating activities:
Net earnings		4,325	4,778	3,304
Adjustments to reconcile net earnings to net cash provided from operating activities:
Equity in earnings of subsidiaries	[1]	(4,458)	(4,666)	(3,373)
Cash dividends received from subsidiaries		2,791	2,060	3,466
Other, net		408	(331)	(203)
Net cash provided (used) by operating activities		3,066	1,841	3,194
Cash flows from investing activities:
Fixed maturity securities sold		483	438	340
Fixed maturity securities purchased		(489)	(484)	(639)
Other investments sold (purchased)		(421)	(711)	(16)
Settlement of derivatives		135	4	22
Additional capitalization of subsidiaries	[1]	(161)	(291)	(214)
Other, net		1	2	87
Net cash provided (used) by investing activities		(452)	(1,042)	(420)
Cash flows from financing activities:
Purchases of treasury stock		(2,301)	(1,537)	(1,627)
Proceeds from borrowings		1,153	1,545	347
Principal payments under debt obligations		(700)	(350)	0
Dividends paid to shareholders		(855)	(769)	(771)
Treasury stock reissued		26	34	49
Proceeds from exercise of stock options		17	12	29
Net change in amount due to/from subsidiary	[1]	43	(89)	(58)
Other, net		(26)	(27)	(2)
Net cash provided (used) by financing activities		(2,643)	(1,181)	(2,033)
Net change in cash and cash equivalents		(29)	(382)	741
Cash and cash equivalents, beginning of period		2,126	2,508	1,767
Cash and cash equivalents, end of period		$ 2,097	$ 2,126	$ 2,508

[1] Eliminated in consolidation