INVESTMENTS - Held-to-Maturity Investments in Debt Securities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	$ 52,540	$ 46,383
Cost or Amortized Cost	52,413	47,009
Gross Unrealized Gains	1,372	992
Gross Unrealized Losses	1,245	1,618
Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	52,540	46,383
Cost or Amortized Cost	52,413	47,009
Gross Unrealized Gains	1,372	992
Gross Unrealized Losses	1,245	1,618
Japan government and agencies \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	27,527	19,071
Cost or Amortized Cost	26,927	18,775
Gross Unrealized Gains	605	297
Gross Unrealized Losses	5	1
Municipalities \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	574	584
Cost or Amortized Cost	539	553
Gross Unrealized Gains	37	35
Gross Unrealized Losses	2	4
Mortgage- and asset-backed Securities \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	120	134
Cost or Amortized Cost	115	129
Gross Unrealized Gains	5	5
Gross Unrealized Losses	0	0
Public Utilities \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	5,426	5,637
Cost or Amortized Cost	5,377	5,615
Gross Unrealized Gains	214	188
Gross Unrealized Losses	165	166
Sovereign and Supranational \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	3,698	4,165
Cost or Amortized Cost	3,633	4,200
Gross Unrealized Gains	167	148
Gross Unrealized Losses	102	183
Banks/financial Institutions \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	10,332	11,480
Cost or Amortized Cost	10,957	12,389
Gross Unrealized Gains	184	170
Gross Unrealized Losses	809	1,079
Other Corporate \| Yen Denominated \| Fixed Maturities
Schedule of Held-to-maturity Securities [Line Items]
Fair Value	4,863	5,312
Cost or Amortized Cost	4,865	5,348
Gross Unrealized Gains	160	149
Gross Unrealized Losses	$ 162	$ 185

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

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Section A

-Paragraph 5

-Chapter 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 17

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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

-Publisher FASB

-Name Accounting Standards Codification

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

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-Publisher FASB

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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

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-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