Name:	met_CededCreditRiskReinsuranceRecoverablesNet
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Period Type:	instant

Percentage of total reinsurance recoverables which constitute a concentration of credit risk.

No definition available.

Name:	met_CededCreditRiskReinsuranceRecoverablesPercentage
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Amount of reinsurance recoverable balances in both asset and liability accounts that have been ceded.

No definition available.

Name:	met_ReinsuranceRecoverablesCeded
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Data Type:	xbrli:monetaryItemType
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_CededCreditRiskLineItems
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Data Type:	xbrli:stringItemType
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Carrying amount of assets as of the balance sheet date pertaining to amounts paid by the insured (including a ceding company) under insurance or reinsurance contracts for which insurance risk is not transferred.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 340
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6387650&loc=d3e9420-108338

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Carrying amount of liabilities as of the balance sheet date pertaining to amounts received by the insurer or reinsurer from the insured (including a ceding company) under insurance or reinsurance contracts for which insurance risk is not transferred.

Name:	us-gaap_DepositContractsLiabilities
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- References

No definition available.

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Stated amount that is the upper retention limit per entity policy.

No definition available.

Name:	us-gaap_ReinsuranceRetentionPolicyAmountRetained
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Percentage of risk reinsured in excess of stated retention per entity policy.

No definition available.

Name:	us-gaap_ReinsuranceRetentionPolicyExcessRetentionPercentage
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_ReinsuranceRetentionPolicyLineItems
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Data Type:	xbrli:stringItemType
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Percentage of risk reinsured on insurance products per entity policy.

No definition available.

Name:	us-gaap_ReinsuranceRetentionPolicyReinsuredRiskPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_ReinsurancePolicyTypeAxis=met_ModifiedCoinsuranceOfClosedBlockMember
Namespace Prefix:
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Name:	us-gaap_ReinsurancePolicyTypeAxis=met_MortalityRiskOnYearlyRenewableTermBasisMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ReinsurancePolicyTypeAxis=met_MortalityRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ReinsurancePolicyTypeAxis=met_MortalityRiskOnCaseByCaseBasisMember
Namespace Prefix:
Data Type:	na
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Name:	us-gaap_CededCreditRiskCollateralizationAxis=us-gaap_CededCreditRiskUnsecuredMember
Namespace Prefix:
Data Type:	na
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Period Type: