Name:	afl_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionReclassificationFromHeldToMaturityToAvailableForSaleDebtSecurities
Namespace Prefix:	afl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

New Accounting Pronouncement Or Change In Accounting Principle Effect Of Adoption UnRealized Gain Loss Net Of Tax Reclassification To Accumulated Other Comprehensive Income

No definition available.

Name:	afl_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionUnRealizedGainLossNetOfTaxReclassificationToAccumulatedOtherComprehensiveIncome
Namespace Prefix:	afl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

New Accounting Pronouncement or Change In Accounting Principle, Cumulative Effect of Change On Assets

No definition available.

Name:	afl_NewAccountingPronouncementorChangeInAccountingPrincipleCumulativeEffectofChangeOnAssets
Namespace Prefix:	afl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Liabilities

No definition available.

Name:	afl_NewAccountingPronouncementorChangeinAccountingPrincipleCumulativeEffectofChangeonLiabilities
Namespace Prefix:	afl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Percentage of Company Assets.

No definition available.

Name:	afl_PercentageOfCompanyAssets
Namespace Prefix:	afl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percentage of Company Revenue.

No definition available.

Name:	afl_PercentageOfCompanyRevenue
Namespace Prefix:	afl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Significant Accounting Policies [Line Items]

No definition available.

Name:	afl_SignificantAccountingPoliciesLineItems
Namespace Prefix:	afl_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

No definition available.

Name:	us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionQuantification
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Name:	us-gaap_StatementBusinessSegmentsAxis=afl_AflacJapanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201613Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=afl_AccountingStandardsUpdate201904Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: