Operations by Segment - Revenues and Pretax Earnings (Detail) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segment Reporting, Revenue Reconciling Item [Line Items]
Earned premiums	$ 4,956	$ 4,333	$ 9,828	$ 8,681
Net investment income	784	727	1,579	1,453
Other income	16	9	44	45
Realized investment gains (losses)	(668)	(89)	(1,247)	(135)
Pretax operating earnings	1,121	978	2,299	1,998
Earnings before income taxes	453	889	1,052	1,863
Income taxes applicable to pretax operating earnings	388	339	795	693
Effect of foreign currency translation on operating earnings	51	12	99	33
Total Revenues	5,088	4,980	10,204	10,044
Aflac Japan
Segment Reporting, Revenue Reconciling Item [Line Items]
Earned premiums	3,770	3,186	7,472	6,393
Net investment income	636	593	1,285	1,186
Other income	5	(1)	25	26
Total business segment revenues	4,411	3,778	8,782	7,605
Pretax operating earnings	931	798	1,911	1,619
Aflac U.S.
Segment Reporting, Revenue Reconciling Item [Line Items]
Earned premiums	1,186	1,147	2,356	2,289
Net investment income	148	135	291	267
Other income	3	3	6	5
Total business segment revenues	1,337	1,285	2,653	2,561
Pretax operating earnings	246	227	499	471
Other business segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total business segment revenues	13	11	28	23
Pretax operating earnings	0	(1)	0	(2)
Total Business Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Total business segment revenues	5,761	5,074	11,463	10,189
Pretax operating earnings	1,177	1,024	2,410	2,088
Corporate
Segment Reporting, Revenue Reconciling Item [Line Items]
Total Revenues	60	49	121	101
Intercompany eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Total Revenues	(65)	(54)	(133)	(111)
Interest Expense, noninsurance operations
Segment Reporting, Revenue Reconciling Item [Line Items]
Pretax operating earnings	(41)	(31)	(82)	(63)
Corporate and eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Pretax operating earnings	$ (15)	$ (15)	$ (29)	$ (27)

Effect of foreign currency translation on operating earnings.

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Income taxes applicable to pretax operating earnings.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

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Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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The income earned from investments in securities and property, equipment and other capital assets. It includes rent from property and equipment, dividends from shares in corporations, and interest from bonds, loans, mortgages, derivatives, commercial paper, bank accounts, certificates of deposits, treasuries, and other financial securities. It does not include realized gains and losses on investments.

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Reflects the sum of all other revenue and income recognized by the entity in the period not otherwise specified in the income statement.

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Premiums earned on the income statement for all insurance and reinsurance contracts after subtracting any amounts ceded to another insurer and adding premiums assumed from other insurers.

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Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains.

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Amount of total revenue for the reportable segments, including revenue from external customers, transactions with other operating segments of the same entity, and (gross) interest revenue. All considered to be "operating revenue" for purposes of the taxonomy.

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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.

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