Name:	met_CallOptionsInEquitySecurities
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

This item represents the estimated amount of gains or losses included in earnings during the period attributable to changes in instrument-specific credit risk arising from loans and other receivables held as assets and other changes in estimated fair value, which were recognized in net investment income.

No definition available.

Name:	met_FairValueOptionChangesInFairValueGainLossRecognizedInNetInvestmentIncome
Namespace Prefix:	met_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	met_FairValueTextualsAbstract
Namespace Prefix:	met_
Data Type:	xbrli:stringItemType
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Estimated number of years until the underlying assets and/or liabilities will be liquidated.

No definition available.

Name:	met_LiquidationPeriodForOtherLimitedPartnershipInterests
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Data Type:	xbrli:durationItemType
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Period Type:	duration

Estimated number of years until the underlying assets and/or liabilities will be liquidated.

No definition available.

Name:	met_LiquidationPeriodForRealEstateJointVentureCommitments
Namespace Prefix:	met_
Data Type:	xbrli:durationItemType
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Period Type:	duration

- Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
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Data Type:	xbrli:stringItemType
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Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

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Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

Name:	us-gaap_FairValueAssetsLevel2ToLevel1TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

The amount of unfunded commitments for which the entity is obligated, to those certain investments for which net asset value per share is calculated (including by unit, membership interest, or other equity (ownership interest) unit measure) (alternative investments).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 6A

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=SL6742756-110258

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Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

Name:	us-gaap_FairValueLiabilitiesLevel1ToLevel2TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.