2.4.0.84044 - Disclosure - Investments (Details 5)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalse$D2013Q2_FixedMaturitiesMemberhttp://www.sec.gov/CIK0001165880duration2013-04-01T00:00:002013-06-30T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$D2012Q2_FixedMaturitiesMemberhttp://www.sec.gov/CIK0001165880duration2012-04-01T00:00:002012-06-30T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDfalsefalse$D2013Q2YTD_FixedMaturitiesMemberhttp://www.sec.gov/CIK0001165880duration2013-01-01T00:00:002013-06-30T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4false USDfalsefalse$D2012Q2YTD_FixedMaturitiesMemberhttp://www.sec.gov/CIK0001165880duration2012-01-01T00:00:002012-06-30T00:00:00USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse1false USDtruefalse$D2013Q2_FixedMaturitiesMemberhttp://www.sec.gov/CIK0001165880duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseFixed maturity investmentsinvest_InvestmentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_FixedMaturitiesMemberinvest_InvestmentAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Fixed maturity investments2true 3invest_InvestmentLineItemsinvest_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments3false 4us-gaap_MarketableSecuritiesRealizedGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse1050000010.5USD$falsetruefalse2truefalsefalse61000006.1USD$falsetruefalse3truefalsefalse2190000021.9USD$falsetruefalse4truefalsefalse1380000013.8USD$falsetruefalsexbrli:monetaryItemTypemonetaryThis item represents the total realized gain (loss) included in earnings for the period as a result of selling marketable securities categorized as trading, available-for-sale, or held-to-maturity. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 false2Net Realized Gains (Losses) on Investments4false 4us-gaap_MarketableSecuritiesUnrealizedGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse-68800000-68.8USD$falsefalsefalse2truefalsefalse70000007.0USD$falsefalsefalse3truefalsefalse-83300000-83.3USD$falsefalsefalse4truefalsefalse2180000021.8USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe aggregate net change in the difference between the fair value and the carrying value, or in the comparative fair values, of marketable securities categorized as trading held at each balance sheet date, that was included in earnings for the period, which may have arisen from (a) securities classified as trading, (b) the unrealized holding gain (loss) on held-to-maturity securities transferred to the trading security category, and (c) the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) on available-for-sale securities transferred to trading securities during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Net Unrealized Gains (Losses) on Investments5false 4mrh_NetForeignExchangeAndIncomeExpenseFromDerivativesmrh_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse-200000-0.2USD$falsefalsefalse2truefalsefalse-1900000-1.9USD$falsefalsefalse3truefalsefalse-4000000-4.0USD$falsefalsefalse4truefalsefalse12000001.2USD$falsefalsefalsexbrli:monetaryItemTypemonetaryRepresents net realized and unrealized foreign exchange gains (losses) from investments and income (expense) derived from investments in the foreign exchange contracts, credit derivatives, interest rate contracts and investment options and futures.No definition available.false2Net Foreign Exchange and Income (Expense) From Certain Derivatives6false 4mrh_TotalChangesInInvestmentCarryingValueInEarningsmrh_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse-58500000-58.5USD$falsefalsefalse2truefalsefalse1120000011.2USD$falsefalsefalse3truefalsefalse-65400000-65.4USD$falsefalsefalse4truefalsefalse3680000036.8USD$falsefalsefalsexbrli:monetaryItemTypemonetaryRepresents the total changes in the carrying value of investments reflected in earnings including net realized and unrealized gains (losses) on investments and net foreign exchange and income (expense) from certain derivatives.No definition available.true2Total Changes in Carrying Value Reflected in Revenues7false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5false USDtruefalse$D2013Q2_EquitySecuritiesMemberhttp://www.sec.gov/CIK0001165880duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseEquity securitiesinvest_InvestmentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EquitySecuritiesMemberinvest_InvestmentAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Equity securities8true 3invest_InvestmentLineItemsinvest_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments9false 4us-gaap_MarketableSecuritiesRealizedGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse3000000.3USD$falsefalsefalse2truefalsefalse7000000.7USD$falsefalsefalse3truefalsefalse6000000.6USD$falsefalsefalse4truefalsefalse2320000023.2USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThis item represents the total realized gain (loss) included in earnings for the period as a result of selling marketable securities categorized as trading, available-for-sale, or held-to-maturity. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 false2Net Realized Gains (Losses) on Investments10false 4us-gaap_MarketableSecuritiesUnrealizedGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse-2600000-2.6USD$falsefalsefalse2truefalsefalse-900000-0.9USD$falsefalsefalse3truefalsefalse-1800000-1.8USD$falsefalsefalse4truefalsefalse-16200000-16.2USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe aggregate net change in the difference between the fair value and the carrying value, or in the comparative fair values, of marketable securities categorized as trading held at each balance sheet date, that was included in earnings for the period, which may have arisen from (a) securities classified as trading, (b) the unrealized holding gain (loss) on held-to-maturity securities transferred to the trading security category, and (c) the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) on available-for-sale securities transferred to trading securities during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Net Unrealized Gains (Losses) on Investments11false 4mrh_NetForeignExchangeAndIncomeExpenseFromDerivativesmrh_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse-900000-0.9USD$falsefalsefalse2truefalsefalse-800000-0.8USD$falsefalsefalse3truefalsefalse-2000000-2.0USD$falsefalsefalse4truefalsefalse-1600000-1.6USD$falsefalsefalsexbrli:monetaryItemTypemonetaryRepresents net realized and unrealized foreign exchange gains (losses) from investments and income (expense) derived from investments in the foreign exchange contracts, credit derivatives, interest rate contracts and investment options and futures.No definition available.false2Net Foreign Exchange and Income (Expense) From Certain Derivatives12false 4mrh_TotalChangesInInvestmentCarryingValueInEarningsmrh_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse-3200000-3.2USD$falsefalsefalse2truefalsefalse-1000000-1.0USD$falsefalsefalse3truefalsefalse-3200000-3.2USD$falsefalsefalse4truefalsefalse54000005.4USD$falsefalsefalsexbrli:monetaryItemTypemonetaryRepresents the total changes in the carrying value of investments reflected in earnings including net realized and unrealized gains (losses) on investments and net foreign exchange and income (expense) from certain derivatives.No definition available.true2Total Changes in Carrying Value Reflected in Revenues13false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse9false USDtruefalse$D2013Q2_OtherInvestmentsMemberhttp://www.sec.gov/CIK0001165880duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseOther investmentsinvest_InvestmentAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_OtherInvestmentsMemberinvest_InvestmentAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Other investments14true 3invest_InvestmentLineItemsinvest_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Investments15false 4us-gaap_MarketableSecuritiesRealizedGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse-3900000-3.9USD$falsefalsefalse2truefalsefalse6000000.6USD$falsefalsefalse3truefalsefalse-6500000-6.5USD$falsefalsefalse4truefalsefalse-1400000-1.4USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThis item represents the total realized gain (loss) included in earnings for the period as a result of selling marketable securities categorized as trading, available-for-sale, or held-to-maturity. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 16 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c)) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 false2Net Realized Gains (Losses) on Investments16false 4us-gaap_MarketableSecuritiesUnrealizedGainLossus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse33000003.3USD$falsefalsefalse2truefalsefalse-200000-0.2USD$falsefalsefalse3truefalsefalse72000007.2USD$falsefalsefalse4truefalsefalse45000004.5USD$falsefalsefalsexbrli:monetaryItemTypemonetaryThe aggregate net change in the difference between the fair value and the carrying value, or in the comparative fair values, of marketable securities categorized as trading held at each balance sheet date, that was included in earnings for the period, which may have arisen from (a) securities classified as trading, (b) the unrealized holding gain (loss) on held-to-maturity securities transferred to the trading security category, and (c) the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) on available-for-sale securities transferred to trading securities during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27357-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27405-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 115 -Paragraph 13, 22 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. false2Net Unrealized Gains (Losses) on Investments17false 4mrh_NetForeignExchangeAndIncomeExpenseFromDerivativesmrh_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse-5400000-5.4USD$falsefalsefalse2truefalsefalse25000002.5USD$falsefalsefalse3truefalsefalse2000000.2USD$falsefalsefalse4truefalsefalse40000004.0USD$falsefalsefalsexbrli:monetaryItemTypemonetaryRepresents net realized and unrealized foreign exchange gains (losses) from investments and income (expense) derived from investments in the foreign exchange contracts, credit derivatives, interest rate contracts and investment options and futures.No definition available.false2Net Foreign Exchange and Income (Expense) From Certain Derivatives18false 4mrh_TotalChangesInInvestmentCarryingValueInEarningsmrh_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse-6000000-6.0USD$falsetruefalse2truefalsefalse29000002.9USD$falsetruefalse3truefalsefalse9000000.9USD$falsetruefalse4truefalsefalse71000007.1USD$falsetruefalsexbrli:monetaryItemTypemonetaryRepresents the total changes in the carrying value of investments reflected in earnings including net realized and unrealized gains (losses) on investments and net foreign exchange and income (expense) from certain derivatives.No definition available.true2Total Changes in Carrying Value Reflected in RevenuesfalseInvestments (Details 5) (USD $)HundredThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.montpelierre.bm/role/DisclosureInvestmentsDetails5418