Number of shares that have been repurchased from the open market during the period

No definition available.

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Namespace Prefix:	afl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Stockholders Equity Note [Line Items]

+ References

No definition available.

+ Details

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

- Definition

The cash outflow to reacquire common stock during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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

- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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

- Definition

The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

SHAREHOLDERS' EQUITY - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Aug. 31, 2017
Stockholders Equity Note [Line Items]
Common stock, share repurchase, dollar amount	$ 296	$ 610
Remaining common stock available for purchase under share repurchase authorizations	91.4
Share Repurchase Program
Stockholders Equity Note [Line Items]
Stock acquired in open market, shares	6.6	17.0
Common stock, share repurchase, dollar amount	$ 296	$ 600
Share Repurchase Authorization 2017
Stockholders Equity Note [Line Items]
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			80.0