Business Basis of Presentation and Summary of Significant Accounting Policies (Details)	9 Months Ended	12 Months Ended
Sep. 30, 2011	Dec. 31, 2010
Business Basis of Presentation and Summary of Significant Accounting Policies (Textuals) [Abstract]
Business Acquisition, Effective Date of Acquisition		November 1, 2010
Business Acquisition, Name of Acquired Entity		American Life Insurance Company (“American Life”) from AM Holdings LLC (formerly known as ALICO Holdings LLC) (“AM Holdings”), a subsidiary of American International Group, Inc. (“AIG”), and Delaware American Life Insurance Company (“DelAm”) from AIG, (American Life, together with DelAm, collectively, “ALICO”)
Period of Acquisition's operations included in MetLife's results	For the three months and nine months ended August 31, 2011
American Life Insurance Company ("American Life") and Delaware American Life Insurance ("DelAm") Member
Business Acquisition [Line Items]
Subsidiary's fiscal year end date	November 30

Month, date and year in which the acquirer obtains control of the acquiree.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=6909708&loc=d3e848-128460

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

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 3

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

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-URI http://asc.fasb.org/extlink&oid=6909708&loc=d3e845-128460

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 10, 11

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 68

-Subparagraph b

-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 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Acquisition Date

-URI http://asc.fasb.org/extlink&oid=6919109

+ Details

- Definition

Disclosure of accounting policy for determining an entity's fiscal year or other fiscal period. This disclosure may include identification of the fiscal period end-date, the length of the fiscal period, any reporting period lag between the entity and its subsidiaries, or equity investees. If a reporting lag exists, the closing date of the entity having a different period end is generally noted, along with an explanation of the necessity for using different closing dates. Any intervening events that materially affect the entity's financial position or results of operations are generally also disclosed.

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