Schedule II - Aflac Incorporated - Aggregate Contractual Maturities of Notes Payable (Detail) $ in Millions	Dec. 31, 2018 USD ($)
Condensed Financial Statements, Captions [Line Items]
2019	$ 5
2020	3
2021	47
2022	351
2023	926
Thereafter	4,494
Total	5,826
Parent Company
Condensed Financial Statements, Captions [Line Items]
2019	0
2020	0
2021	45
2022	350
2023	925
Thereafter	4,493
Total	$ 5,813

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(a))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

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-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601

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