2.4.0.82404426 - Disclosure - Investments (Cash Equivalents - Narrative) (Details)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalse$I2013Q2http://www.sec.gov/CIK0000733076instant2013-06-30T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$I2012Q4http://www.sec.gov/CIK0000733076instant2012-12-31T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 1us-gaap_InvestmentsDebtAndEquitySecuritiesAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments, Debt and Equity Securities [Abstract]2false 2us-gaap_CashEquivalentsAtCarryingValueus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse461000000461USD$falsetruefalse2truefalsefalse654000000654USD$falsetruefalsexbrli:monetaryItemTypemonetaryAmount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.1) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 false2Cash equivalentsfalseInvestments (Cash Equivalents - Narrative) (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.metlife.com/role/InvestmentsCashEquivalentsNarrativeDetails22