BUSINESS SEGMENT INFORMATION AND SELECTED FOREIGN CURRENCY TRANSLATION ITEMS - Operations by Segment - Pretax Earnings (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total revenues		$ 17,164	$ 18,927	$ 18,701
Benefits and claims, excluding reserve remeasurement		7,987	8,008	8,594
Reserve remeasurement (gains) losses		(694)	(558)	(383)
Total benefits and claims, net		7,293	7,450	8,211
Amortization of deferred policy acquisition costs		874	851	816
Insurance commissions		991	998	1,052
Insurance and other expenses		3,253	3,014	3,165
Total benefits and expenses		12,631	12,510	13,439
Net investment gains (losses)		(572)	1,271	590
Earnings before income taxes		4,533	6,417	5,262
Income taxes applicable to pretax adjusted earnings		954	873	577
Effect of foreign currency translation on after-tax adjusted earnings		19	(103)	(113)
Remeasurement gain (loss), deferred profit liability for limited-payment contracts		(52)	(81)	20
Change in value of federal historic rehabilitation and solar tax credit investments		(65)	(165)	(343)
Federal historic rehabilitation and solar tax credits, amount		69	164	334
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total revenues		17,537	17,405	17,747
Total benefits and expenses		12,575	12,460	13,437
Pretax adjusted earnings		4,962	4,945	4,310
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other income (loss)		(54)	(23)	39
Net investment gains (losses)		(572)	1,271	590
Amortized hedge costs		45	26	157
Amortized hedge income		(98)	(113)	(121)
Net interest (income) expense from derivatives associated with certain investment strategies		252	338	328
Impact of interest from derivatives associated with notes payable		(2)	(27)	(41)
Aflac Japan
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total benefits and claims, net		3,999	4,317	5,313
Amortization of deferred policy acquisition costs		323	321	326
Earnings before income taxes		3,321
Aflac Japan | Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total revenues	[1]	9,357	9,659	10,664
Benefits and claims, excluding reserve remeasurement		4,528	4,761	5,409
Reserve remeasurement (gains) losses		(529)	(444)	(96)
Total benefits and claims, net		3,999	4,317	5,313
Amortization of deferred policy acquisition costs		323	321	326
Insurance commissions		427	435	491
Insurance and other expenses		1,168	1,092	1,300
Total benefits and expenses		5,917	6,165	7,430
Pretax adjusted earnings	[1]	3,440	3,494	3,234
Aflac U.S.
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total benefits and claims, net		2,837	2,726	2,431
Amortization of deferred policy acquisition costs		551	530	490
Earnings before income taxes		1,212
Aflac U.S. | Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total revenues		6,903	6,739	6,623
Benefits and claims, excluding reserve remeasurement		2,969	2,821	2,715
Reserve remeasurement (gains) losses		(132)	(95)	(284)
Total benefits and claims, net		2,837	2,726	2,431
Amortization of deferred policy acquisition costs		551	530	490
Insurance commissions		564	563	561
Insurance and other expenses		1,530	1,501	1,640
Total benefits and expenses		5,482	5,320	5,122
Pretax adjusted earnings		1,421	1,419	1,501
Corporate and other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total benefits and claims, net		458	407	467
Amortization of deferred policy acquisition costs		0	0	0
Corporate and other | Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total revenues	[2]	1,277	1,007	460
Total benefits and expenses		1,176	975	885
Pretax adjusted earnings	[2]	$ 101	$ 32	$ (425)

[1] Includes a gain (loss) of $(52), $(81) and $20 in 2025, 2024 and 2023, respectively, related to remeasurement of the deferred profit liability for limited-payment contracts.

[2] The change in value of federal historic rehabilitation and solar investments in partnerships of $65, $165 and $343 in 2025, 2024 and 2023, respectively, is included as a reduction to net investment income. Tax credits on these investments of $69, $164 and $334 in 2025, 2024 and 2023, respectively, have been reported as an income tax benefit in the consolidated statements of earnings. See Note 1 for additional information on these investments.