The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of options outstanding, including both vested and non-vested options.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=afl_Range1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=afl_Range2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=afl_Range3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=afl_Range4Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis=afl_Range5Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

SHARE-BASED COMPENSATION - Stock Options Outstanding and Exercisable (Detail) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	$ 0.00
Range of Exercise Prices Per Share - Upper Range	$ 44.59
Options Outstanding - Stock Option Shares	2,145	3,045	3,706	5,330
Options outstanding - weighted-average remaining term (Yrs)	3 years 4 months 24 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 31.02	$ 30.25	$ 29.65	$ 28.54
Options Exercisable - Stock Option Shares	2,145	2,986	3,553
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 31.02
$0.00 - $24.75
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	0.00
Range of Exercise Prices Per Share - Upper Range	$ 24.75
Options Outstanding - Stock Option Shares	336
Options outstanding - weighted-average remaining term (Yrs)	8 months 12 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 24.09
Options Exercisable - Stock Option Shares	336
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 24.09
$24.75 - $28.97
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	24.75
Range of Exercise Prices Per Share - Upper Range	$ 28.97
Options Outstanding - Stock Option Shares	370
Options outstanding - weighted-average remaining term (Yrs)	3 years 10 months 24 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 28.85
Options Exercisable - Stock Option Shares	370
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 28.85
$28.97 - $31.21
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	28.97
Range of Exercise Prices Per Share - Upper Range	$ 31.21
Options Outstanding - Stock Option Shares	718
Options outstanding - weighted-average remaining term (Yrs)	2 years 9 months 18 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 30.74
Options Exercisable - Stock Option Shares	718
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 30.74
$31.21 - $36.21
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	31.21
Range of Exercise Prices Per Share - Upper Range	$ 36.21
Options Outstanding - Stock Option Shares	572
Options outstanding - weighted-average remaining term (Yrs)	4 years 8 months 12 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 34.36
Options Exercisable - Stock Option Shares	572
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 34.36
$36.21 - $44.59
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Range of Exercise Prices Per Share - Lower Range	36.21
Range of Exercise Prices Per Share - Upper Range	$ 44.59
Options Outstanding - Stock Option Shares	149
Options outstanding - weighted-average remaining term (Yrs)	5 years 9 months 18 days
Options Outstanding - Weighted-Average Exercise Price Per Share	$ 40.57
Options Exercisable - Stock Option Shares	149
Options Exercisable - Weighted-Average Exercise Price Per Share	$ 40.57