This represents the recorded investment for impaired mortgage loans held-for-investment.

No definition available.

Name:	met_RecordedInvestmentForImpairedMortgageLoansHeldForInvestment
Namespace Prefix:	met_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 recorded investment related to impaired financing receivables.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=6965416&loc=SL6953550-111524

-Subparagraph (b)

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The unpaid principal balance related to impaired financing receivables.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=6965416&loc=d3e5212-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_LoanAndLeaseReceivablesImpairedAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Investments (Details 36) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Impaired Mortgage Loans
Unpaid Principal Balance	$ 593	$ 507
Valuation allowances	481	664	721	304
Carrying value	470	403
Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	269	269
Recorded Investment	268	269
Valuation allowances	105	88
Carrying value	163	181
Loans Without Valuation Allowances [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	324	238
Carrying value	307	222
Commercial mortgage loans portfolio segment [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	348	219
Valuation allowances	398	562	589	232
Carrying value	274	171
Commercial mortgage loans portfolio segment [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	96	120
Recorded Investment	96	120
Valuation allowances	59	36
Carrying value	37	84
Commercial mortgage loans portfolio segment [Member] \| Loans Without Valuation Allowances [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	252	99
Carrying value	237	87
Agricultural mortgage loans portfolio segment [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	231	269
Valuation allowances	81	88	115	61
Carrying value	183	213
Agricultural mortgage loans portfolio segment [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	160	146
Recorded Investment	159	146
Valuation allowances	45	52
Carrying value	114	94
Agricultural mortgage loans portfolio segment [Member] \| Loans Without Valuation Allowances [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	71	123
Carrying value	69	119
Residential mortgage loans portfolio segment [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	14	19
Valuation allowances	2	14	17	11
Carrying value	13	19
Residential mortgage loans portfolio segment [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	13	3
Recorded Investment	13	3
Valuation allowances	1	0
Carrying value	12	3
Residential mortgage loans portfolio segment [Member] \| Loans Without Valuation Allowances [Member]
Impaired Mortgage Loans
Unpaid Principal Balance	1	16
Carrying value	$ 1	$ 16