Cash Flow Hedging Activity, Maximum Time Period

No definition available.

Name:	afl_Cashflowhedgingactivitymaximumtimeperiod
Namespace Prefix:	afl_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

Total number of counterparties to derivative contracts.

+ References

No definition available.

+ Details

Name:	afl_NumberOfCounterparties
Namespace Prefix:	afl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of counterparties that comprise majority of aggregate notional amount of swaps

+ References

No definition available.

+ Details

Name:	afl_NumberOfCounterpartiesThatCompriseMajorityOfAggregateNotionalAmountOfSwaps
Namespace Prefix:	afl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of the notional amount of swaps from certain number of counterparties

+ References

No definition available.

+ Details

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

- Definition

The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624258-113959

+ Details

Name:	us-gaap_AdditionalCollateralAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624177-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

+ Details

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

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

- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4H
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624258-113959

+ Details

Name:	us-gaap_DerivativeNetLiabilityPositionAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_NetInvestmentHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=afl_SeniorNotesTwoPointFourZeroPercentDueMarchTwentyTwentyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=afl_SeniorNotesFourPointZeroZeroPercentDueFebruaryTwentyTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=afl_SeniorNotesThreePointSixTwoFivePercentDueJuneTwentyTwentyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=afl_SeniorNotesThreePointSixTwoFivePercentDueNovemberTwentyTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=afl_SeniorNotesThreePointTwoFivePercentDueMarchTwentyTwentyFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

DERIVATIVE INSTRUMENTS - Additional Information (Detail) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) yr counterparties	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) yr counterparties	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Cash flow hedging activity, maximum time period \| yr	8		8
Number of counterparties \| counterparties	15		15
Number of counterparties that comprise majority of aggregate notional amount of swaps \| counterparties	4		4
Percentage of notional amount of swaps from certain number of counterparties	60.00%		60.00%
Derivative, Net Liability Position, Aggregate Fair Value	$ 160		$ 160		$ 264
Additional Collateral, Aggregate Fair Value	36		36
Net investment hedge
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	$ 0	0	$ 0
2.40% senior notes due March 2020
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	550		550
4.00% senior notes due February 2022
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	350		350
3.625% senior notes due June 2023
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	700		700
3.625% senior notes due November 2024
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	750		750
3.25% senior notes due March 2025
Derivative Instruments and Hedging Activities Disclosure [Line Items]
Debt instrument, principal amount	$ 450		$ 450