This caption presents the carrying value of mortgage loans held by securitization entities for which the Company has elected the fair value option.

Name:	met_CommercialMortgageLoansHeldByConsolidatedSecuritizationEntitiesFairValueOption
Namespace Prefix:	met
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The balance represents the amount of loans that are secured by real estate mortgages.

+ Details

Name:	met_MortgageLoansHeldForInvestment
Namespace Prefix:	met
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Mortgage loans held-for-sale.

+ Details

Name:	met_MortgageLoansHeldForSaleAbstract
Namespace Prefix:	met
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of Allowance For Loan And Lease Losses on Real Estate to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfAllowanceForLoanAndLeaseLossesRealEstateToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Commercial Mortgage Loans Held By Consolidated Securitization Entities Fair Value Option to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfCommercialMortgageLoansHeldByConsolidatedSecuritizationEntitiesFairValueOptionToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Consumer Mortgage Loans and Leases Receivable to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfLoansAndLeasesReceivableConsumerMortgageToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Loans Held For Sale, Mortgages to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfLoansHeldForSaleMortgagesToMortgagesLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Loans Held For Sale, Other to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfLoansHeldForSaleOtherToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Commercial Agricultural Loans Receivable to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfLoansReceivableCommercialAgriculturalToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Commercial Mortgage Loans Receivable to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfLoansReceivableCommercialMortgageToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Loans Receivable Held For Sale, Net to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfLoansReceivableHeldForSaleNetToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Mortgage Loans Held-for-investment, net to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfMortgageLoansHeldForInvestmentNetToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Mortgage Loans Held For Investment to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfMortgageLoansHeldForInvestmentToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Commercial Agricultural Loans Receivable to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfMortgageLoansOnRealEstateCommercialAndConsumerNetToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Mortgage Loans On Real Estate to total Mortgage Loans on Real Estate.

+ Details

Name:	met_PercentageOfMortgageLoansOnRealEstateToMortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	met
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6873192&loc=d3e21338-158488

+ Details

Name:	us-gaap_AllowanceForLoanAndLeaseLossesRealEstate
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The gross carrying amount of mortgage loans to individuals. This item excludes subordinated loans such as home equity lines of credit.

+ References

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

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Subsection I

-Paragraph 8

-Subparagraph c(i)

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-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 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(3),(b))

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

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph a, b

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Chapter 8

-Paragraph 40, 41

-IssueDate 2006-05-01

-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.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableConsumerMortgage
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the aggregate carrying amount of all categories of loans and leases held in portfolio, net of unearned income and the allowance for losses on loans and leases.

+ References

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7)

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

+ Details

Name:	us-gaap_LoansAndLeasesReceivableNetReportedAmount
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Carrying amount of mortgage loans to individuals not classified as held for investment but are held-for-sale.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6490309&loc=d3e48678-111004

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(3))

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

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

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Subsection I

-Paragraph 8

-Subparagraph h

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Permanent Investor

-URI http://asc.fasb.org/extlink&oid=6520390

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 65

-Paragraph 1, 34

-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 Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

+ Details

Name:	us-gaap_LoansHeldForSaleMortgages
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the carrying amount of loans held for sale not otherwise specified in the existing taxonomy.

+ References

+ Details

Name:	us-gaap_LoansHeldForSaleOther
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the gross carrying amount of agricultural loans receivable as of the balance sheet date. In general, agricultural loans consist of borrowings used to finance major equipment and machinery purchases and expenses, livestock or crop production (including fisheries), and to supplement working capital needs of an entity engaged in farming operations.

+ References

+ Details

Name:	us-gaap_LoansReceivableCommercialAgricultural
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the gross carrying amount of unpaid loans issued to businesses to provide financing on existing land or a building, which, pursuant to terms of the underlying debt instrument, are secured at a minimum but possibly exclusively by that real property. Mortgages represent permanent financing, and are issued to replace previously existing mortgages or pay off acquisition, development and construction loans, or to provide cash to the borrower.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5066-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a)(3))

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

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-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 SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph a

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

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Chapter 8

-Paragraph 51

-IssueDate 2006-05-01

-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.

+ Details

Name:	us-gaap_LoansReceivableCommercialMortgage
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The aggregate carrying amount of loans receivable that will be sold to other entities. Includes mortgage and all other loans (collectively, loans) not classified as held for investment. Such loans are stated at the lower of cost or market, or elected fair value. Mortgage loans exclude mortgage-backed securities which are considered a debt security (other loan).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a))

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

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

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph d

-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 65

-Paragraph 4, 5, 6, 7, 9, 12, 28, 29

-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 310

-SubTopic 10

-Section 35

-Paragraph 49

-URI http://asc.fasb.org/extlink&oid=6949992&loc=d3e3084-111518

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 9

-Section 03

-Paragraph 7

-Subparagraph a

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section 30

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6490209&loc=d3e48214-111002

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

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Chapter V

-Section 563c.102

-Subsection I

-Paragraph 8

-Subparagraph h

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 65

-Paragraph 4

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6375948&loc=d3e4428-111522

+ Details

Name:	us-gaap_LoansReceivableHeldForSaleNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Total carrying amount of mortgage loans as of the balance sheet date.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-29.6)

-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule IV

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 29

-Article 12

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule IV)

-URI http://asc.fasb.org/extlink&oid=6882300&loc=d3e5864-122674

+ Details

Name:	us-gaap_MortgageLoansOnRealEstate
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 1

-Subparagraph c

Reference 3: 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(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_MortgageLoansOnRealEstateCommercialAndConsumerNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_NotesAndLoansReceivableNetCurrentAbstract
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Investments (Details 30) (USD $) In Millions, unless otherwise specified	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Dec. 31, 2009
Company-held mortgage loans held-for-investment, net
Commercial mortgage loans	$ 40,120		$ 37,818
Percentage of loans receivable on commercial mortgage loans	63.80%		60.70%
Agricultural mortgage loans	12,967		12,751
Percentage of loans receivable on agricultural mortgage loans	20.60%		20.40%
Residential mortgage loans	3,424		2,231
Percentage of loans receivable on residential mortgage loans	5.40%		3.70%
Subtotal	56,511		52,800
Percentage of loans receivable on subtotal	89.80%		84.80%
Valuation allowances	(529)	(566)	(664)	(666)	(734)	(721)
Percentage of loans receivable on valuation allowances	(0.80%)		(1.10%)
Subtotal mortgage loans held-for-investment, net	55,982		52,136
Percentage of loans receivable on subtotal mortgage loans held-for-investment, net	89.00%		83.70%
Commercial mortgage loans held by consolidated securitization entities - fair value option	3,227		6,840
Percentage of loans receivable on commercial mortgage loans held by consolidated securitization entities - fair value option	5.10%		11.00%
Mortgage loans, at estimated fair value, relating to variable interest entities	59,209		58,976
Percentage of loans receivable on mortgage loans, at estimated fair value, relating to variable interest entities	94.10%		94.70%
Mortgage loans held-for-sale
Residential mortgage loans - FVO	2,590		2,510
Percentage of loans held for sale on residential mortgage loans - FVO	4.10%		4.00%
Mortgage loans - lower of amortized cost or estimated fair value	1,150		811
Percentage of loans held for sale on mortgage loans - lower of amortized cost or estimated fair value	1.80%		1.30%
Held-for-sale, principally at estimated fair value	3,740		3,321
Percentage of loans held for sale on held-for-sale, principally at estimated fair value	5.90%		5.30%
Total mortgage loans, net	$ 62,949		$ 62,297
Percentage of loans held for sale on total mortgage loans, net	100.00%		100.00%