BUSINESS SEGMENT INFORMATION - Operations by Segment - Revenues (Details) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) segment	Sep. 30, 2022 USD ($)
Segment Reporting, Revenue Reconciling Item [Line Items]
Number of reportable insurance business segments | segment				2
Net earned premiums	[1]	$ 3,476	$ 3,535	$ 10,737	$ 11,379
Other income		47	50	139	168
Total revenues		4,950	4,704	14,923	15,192
Total adjusted revenues		4,436	4,468	13,527	14,230
Net investment gains (losses)	[2],[3],[4],[5]	514	236	1,396	962
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		22	(41)	22	(42)
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums	[1]	1,973	2,125	6,207	7,084
Adjusted net investment income	[2],[4]	679	663	1,927	2,066
Other income		8	9	26	26
Total revenues		2,660	2,797	8,160	9,176
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		22	(41)	22	(42)
Hedge costs		26	28	148	84
Net interest cash flows from derivatives		(79)	(25)	(214)	(37)
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		1,419	1,375	4,272	4,182
Adjusted net investment income	[5]	209	185	609	563
Other income		33	38	102	120
Total revenues		1,661	1,598	4,983	4,865
Net interest cash flows from derivatives		(9)	(1)	(24)	1
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net earned premiums		83	35	258	112
Total revenues	[3],[6]	115	73	384	189
Hedge income		25	19	92	44
Change in value of federal historic rehabilitation and solar tax credit investments		(64)	(19)	(169)	(61)
Federal historic rehabilitation and solar tax credits, amount		$ 63	$ 19	$ 171	$ 63

[1] Includes a gain (loss) of $22 and $(41) for the three-month periods and $22 and $(42) for the nine-month periods ended September 30, 2023 and 2022, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.

[2] Amortized hedge costs of $26 and $28 for the three-month periods and $148 and $84 for the nine-month periods ended September 30, 2023, and 2022, respectively, related to certain foreign currency exposure management strategies have been reclassified from net investment gains (losses) and reported as a deduction from net investment income when analyzing operations.

[3] Amortized hedge income of $25 and $19 for the three-month periods and $92 and $44 for the nine-month periods ended September 30, 2023, and 2022, respectively, related to certain foreign currency exposure management strategies has been reclassified from net investment gains (losses) and reported as an increase to net investment income when analyzing operations.

[4] Net interest cash flows from derivatives associated with certain investment strategies of $(79) and $(25) for the three-month periods and $(214) and $(37) for the nine-month periods ended September 30, 2023, and 2022, respectively, have been reclassified from net investment gains (losses) and included in adjusted earnings as a component of net investment income when analyzing operations.

[5] Net interest cash flows from derivatives associated with certain investment strategies of $(9) and $(1) for the three-month periods and $(24) and $1 for the nine-month periods ended September 30, 2023, and 2022, have been reclassified from net investment gains (losses) and included in adjusted earnings as a component of net investment income when analyzing operations.

[6] The change in value of federal historic rehabilitation and solar investments in partnerships of $64 and $19 for the three-month periods and $169 and $61 for the nine-month periods ended September 30, 2023, and 2022, respectively, is included as a reduction to net investment income. Tax credits on these investments of $63 and $19 for the three-month periods and $171 and $63 for the nine-month periods ended September 30, 2023, and 2022, respectively, have been recorded as an income tax benefit in the consolidated statements of earnings. See Note 3 for additional information on these investments.