XML 30 R77.htm IDEA: XBRL DOCUMENT v2.4.1.9
Derivatives (Hedges of Net Investments in Foreign Operations) (Details) (Foreign Operations Hedges [Member], USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of Gains (Losses) Deferred in AOCI (Effective Portion) $ 70met_GainsLossesDeferredInAccumulatedOtherComprehensiveIncomeLossOnDerivativesEffectivePortion $ (148)met_GainsLossesDeferredInAccumulatedOtherComprehensiveIncomeLossOnDerivativesEffectivePortion
Foreign currency forwards
    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of Gains (Losses) Deferred in AOCI (Effective Portion) 111met_GainsLossesDeferredInAccumulatedOtherComprehensiveIncomeLossOnDerivativesEffectivePortion
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeForwardMember
/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis
= us-gaap_NetInvestmentHedgingMember		 (34)met_GainsLossesDeferredInAccumulatedOtherComprehensiveIncomeLossOnDerivativesEffectivePortion
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeForwardMember
/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis
= us-gaap_NetInvestmentHedgingMember
Currency options
    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount of Gains (Losses) Deferred in AOCI (Effective Portion) $ (41)met_GainsLossesDeferredInAccumulatedOtherComprehensiveIncomeLossOnDerivativesEffectivePortion
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeOptionMember
/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis
= us-gaap_NetInvestmentHedgingMember		 $ (114)met_GainsLossesDeferredInAccumulatedOtherComprehensiveIncomeLossOnDerivativesEffectivePortion
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeOptionMember
/ us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis
= us-gaap_NetInvestmentHedgingMember