2.4.0.82404419 - Disclosure - Investments (Components of Net Investment Gains Losses) (Details)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalse$D2013Q2QTDhttp://www.sec.gov/CIK0000733076duration2013-04-01T00:00:002013-06-30T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$D2012Q2QTDhttp://www.sec.gov/CIK0000733076duration2012-04-01T00:00:002012-06-30T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDfalsefalse$D2013Q2YTDhttp://www.sec.gov/CIK0000733076duration2013-01-01T00:00:002013-06-30T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4false USDfalsefalse$D2012Q2YTDhttp://www.sec.gov/CIK0000733076duration2012-01-01T00:00:002012-06-30T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 4us-gaap_MarketableSecuritiesGainLossAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Marketable Securities, Gain (Loss) [Abstract]2false 5us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNetus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse-2000000-2USD$falsetruefalse2truefalsefalse-14000000-14USD$falsetruefalse3truefalsefalse-14000000-14USD$falsetruefalse4truefalsefalse-35000000-35USD$falsetruefalsexbrli:monetaryItemTypemonetaryThe amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. 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Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 false2Other investment portfolio gains (losses)12false 3micc_InvestmentPortfolioGainsLossesmicc_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse1400000014USD$falsefalsefalse2truefalsefalse6600000066USD$falsefalsefalse3truefalsefalse7800000078USD$falsefalsefalse4truefalsefalse6500000065USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThis item represents the subtotal of gains (losses)on the investment portfolio.No definition available.false2Subtotal - investment portfolio gains (losses)13true 3micc_ConsolidatedSecuritizationEntitiesAbstractmicc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0FVO CSEs - changes in estimated fair value:14false 4micc_GainsLossesOnCommercialMortgageLoansHeldByConsolidatedSecuritizationEntitiesFairValueOptionmicc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse-23000000-23USD$falsefalsefalse2truefalsefalse-7000000-7USD$falsefalsefalse3truefalsefalse-36000000-36USD$falsefalsefalse4truefalsefalse-1000000-1USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe net gain or loss resulting from the change in fair value of commercial mortgage loans held by consolidated securitization entities not required to be reported separately in the statement of income for which the Company has elected the fair value option.No definition available.false2Commercial mortgage loans15false 3micc_GainsLossesOnLongTermDebtOfConsolidatedSecuritizationEntitiesRelatedToMortgageLoansFairValueOptionmicc_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse2800000028USD$falsefalsefalse2truefalsefalse1300000013USD$falsefalsefalse3truefalsefalse5000000050USD$falsefalsefalse4truefalsefalse1100000011USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe net gain or loss resulting from the sale or disposal of long-term debt relating to mortgage loans of consolidated securitization entities not required to be reported separately in the statement of income for which the Company has elected the fair option.No definition available.false2Long-term debt - related to commercial mortgage loans16false 3us-gaap_GainsLossesOnSalesOfOtherAssetsus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse-3000000-3USD$falsefalsefalse2truefalsefalse-1000000-1USD$falsefalsefalse3truefalsefalse-10000000-10USD$falsefalsefalse4truefalsefalse00USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe net gain (loss) resulting from the sale or disposal of assets not required to be reported separately in the statement of income.No definition available.false2Non-investment portfolio gains (losses)17false 3micc_GainsLossesOnAssetsAndLiabilitiesHeldByConsolidatedSecuritizationsEntitiesUnderFairValueOptionAndAllOtherGainsLossesmicc_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse20000002USD$falsefalsefalse2truefalsefalse50000005USD$falsefalsefalse3truefalsefalse40000004USD$falsefalsefalse4truefalsefalse1000000010USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe net gain or loss incurred on assets and liabilities held by consolidated securitizations entities and all other gains and losses.No definition available.false2Subtotal FVO CSEs and non-investment portfolio gains (losses)18false 3us-gaap_GainLossOnInvestmentsus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse1600000016USD$falsefalsefalse2truefalsefalse7100000071USD$falsefalsefalse3truefalsefalse8200000082USD$falsefalsefalse4truefalsefalse7500000075USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThis item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. 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This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Total OTTI losses recognized in earnings47false 5us-gaap_RealizedInvestmentGainsLossesus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse30000003USD$falsefalsefalse2truefalsefalse20000002USD$falsefalsefalse3truefalsefalse30000003USD$falsefalsefalse4truefalsefalse-3000000-3USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.3(a)) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 325 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6485959&loc=d3e22529-158502 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 3 -Subparagraph a -Article 7 false2Net investment gains (losses)48false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse41false USDtruefalse$D2013Q2QTD_us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis_us-gaap_NonredeemablePreferredStockMemberhttp://www.sec.gov/CIK0000733076duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseNon-redeemable preferred stock [Member]us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_NonredeemablePreferredStockMemberus-gaap_MajorTypesOfDebtAndEquitySecuritiesAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Non-redeemable preferred stock [Member]49true 4us-gaap_MarketableSecuritiesGainLossAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Marketable Securities, Gain (Loss) [Abstract]50false 5us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNetus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse00USD$falsefalsefalse2truefalsefalse00USD$falsefalsefalse3truefalsefalse-3000000-3USD$falsefalsefalse4truefalsefalse00USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. 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