INVESTMENTS - Held-to-Maturity Investments in Debt Securities (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	$ 60,054	$ 47,009
Gross Unrealized Gains	1,831	992
Gross Unrealized Losses	628	1,618
Fair Value	61,257	46,383
Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	60,054	47,009
Gross Unrealized Gains	1,831	992
Gross Unrealized Losses	628	1,618
Fair Value	61,257	46,383
Japan government and agencies \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	34,792	18,775
Gross Unrealized Gains	715	297
Gross Unrealized Losses	6	1
Fair Value	35,501	19,071
Municipalities \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	550	553
Gross Unrealized Gains	42	35
Gross Unrealized Losses	0	4
Fair Value	592	584
Mortgage- and asset-backed Securities \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	109	129
Gross Unrealized Gains	5	5
Gross Unrealized Losses	0	0
Fair Value	114	134
Public Utilities \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	5,494	5,615
Gross Unrealized Gains	328	188
Gross Unrealized Losses	66	166
Fair Value	5,756	5,637
Sovereign and Supranational \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	3,712	4,200
Gross Unrealized Gains	230	148
Gross Unrealized Losses	79	183
Fair Value	3,863	4,165
Banks/financial Institutions \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	10,425	12,389
Gross Unrealized Gains	272	170
Gross Unrealized Losses	399	1,079
Fair Value	10,298	11,480
Other Corporate \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Cost or Amortized Cost	4,972	5,348
Gross Unrealized Gains	239	149
Gross Unrealized Losses	78	185
Fair Value	$ 5,133	$ 5,312

For an unclassified balance sheet, this item represents investments in debt securities which are categorized as held-to-maturity. The held-to-maturity category is for those securities that the entity has the positive intent and ability to hold until maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 210

-Section S99

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-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 4

-Chapter 3

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-Number 115

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.6)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

- Definition

This item represents the aggregate fair value of investments in debt securities as of the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details

- Definition

As of the balance sheet date, the excess of fair value over carrying value (amortized cost) of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding gain.

+ References+ Details

- Definition

As of the balance sheet date, the excess of carrying value (amortized cost) over fair value of a debt security categorized as held-to-maturity, exclusive of dividend or interest income recognized but not yet received and exclusive of any write-downs for other-than-temporary impairment. Such item represents the gross unrecognized holding loss.

+ References+ Details