2.4.0.840412 - Disclosure - Investments In Unconsolidated Joint Ventures (Stamford SM LLC) (Narrative) (Details)truefalsefalse1false falsefalseAs_Of_7_15_2013http://www.sec.gov/CIK0000924901instant2013-07-15T00:00:000001-01-01T00:00:00Unit16Standardhttp://www.xbrl.org/2003/instancepurexbrli02false USDtruefalse$Duration_2_16_2012_To_2_17_2012_us-gaap_RealEstatePropertiesAxis_cli_ClassPortfolioInStamfordConnecticutMemberhttp://www.sec.gov/CIK0000924901duration2012-02-16T00:00:002012-02-17T00:00:00falsefalseClass A Portfolio In Stamford, Connecticut [Member]us-gaap_RealEstatePropertiesAxisxbrldihttp://xbrl.org/2006/xbrldicli_ClassPortfolioInStamfordConnecticutMemberus-gaap_RealEstatePropertiesAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit12Standardhttp://www.xbrl.org/2009/utrsqftutr0USDUSD$3false truefalseAs_Of_2_17_2012_us-gaap_RealEstatePropertiesAxis_cli_ClassOfficeSpaceMemberhttp://www.sec.gov/CIK0000924901instant2012-02-17T00:00:000001-01-01T00:00:00falsefalseClass A Office Space [Member]us-gaap_RealEstatePropertiesAxisxbrldihttp://xbrl.org/2006/xbrldicli_ClassOfficeSpaceMemberus-gaap_RealEstatePropertiesAxisexplicitMemberUnit19Standardhttp://www.mack-cali.com/20130630propertycli0Unit12Standardhttp://www.xbrl.org/2009/utrsqftutr04false truefalseAs_Of_2_17_2012_us-gaap_RealEstatePropertiesAxis_cli_ResidentialSpaceMemberhttp://www.sec.gov/CIK0000924901instant2012-02-17T00:00:000001-01-01T00:00:00falsefalseResidential Space [Member]us-gaap_RealEstatePropertiesAxisxbrldihttp://xbrl.org/2006/xbrldicli_ResidentialSpaceMemberus-gaap_RealEstatePropertiesAxisexplicitMemberUnit17Standardhttp://www.mack-cali.com/20130630itemcli0Unit12Standardhttp://www.xbrl.org/2009/utrsqftutr05false truefalseDuration_1_1_2013_To_6_30_2013_us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis_cli_StamfordSMLLCMemberhttp://www.sec.gov/CIK0000924901duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseStamford SM LLC [Member]us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxisxbrldihttp://xbrl.org/2006/xbrldicli_StamfordSMLLCMemberus-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxisexplicitMemberUnit16Standardhttp://www.xbrl.org/2003/instancepurexbrli06false USDtruefalse$Duration_1_1_2013_To_6_30_2013_us-gaap_DebtInstrumentAxis_cli_MezzLoanMemberhttp://www.sec.gov/CIK0000924901duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseMezz Loan [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldicli_MezzLoanMemberus-gaap_DebtInstrumentAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/iso4217USDiso42170Unit16Standardhttp://www.xbrl.org/2003/instancepurexbrli0USDUSD$7false USDtruefalse$As_Of_2_17_2012_us-gaap_DebtInstrumentAxis_cli_MezzLoanMemberhttp://www.sec.gov/CIK0000924901instant2012-02-17T00:00:000001-01-01T00:00:00falsefalseMezz Loan [Member]us-gaap_DebtInstrumentAxisxbrldihttp://xbrl.org/2006/xbrldicli_MezzLoanMemberus-gaap_DebtInstrumentAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_ScheduleOfEquityMethodInvestmentsLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Schedule of Equity Method Investments [Line Items]2false 4us-gaap_AreaOfRealEstatePropertyus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalse2truefalsefalse17000001700000falsefalsefalse3truefalsefalse16700001670000falsefalsefalse4truefalsefalse7050070500falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalsenum:areaItemTypedecimalArea of a real estate property.No definition available.false256Area of property (in square feet)3false 4cli_VenturePropertyAcquisitionCostcli_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2truefalsefalse4000000040000000USD$falsetruefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryCost of property acquired by the venture.No definition available.false2Venture property acquisition cost4false 4us-gaap_MortgageLoansOnRealEstateFaceAmountOfMortgagesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7truefalsefalse5000000050000000falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of the contractual principal due at the origination of the mortgage loan (face amount).Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule IV) -URI http://asc.fasb.org/extlink&oid=6882300&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 29 -Article 12 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph c -Subparagraph Schedule IV -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29) -URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014 false2Mortgage loan face amount5false 4us-gaap_NumberOfRealEstatePropertiesus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3truefalsefalse77falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalsexbrli:integerItemTypeintegerThe number of real estate properties owned as of the balance sheet date.No definition available.false256Number of properties6false 4us-gaap_NumberOfUnitsInRealEstatePropertyus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalsenetLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse106106falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalsexbrli:integerItemTypeintegerThe number of units in a real estate property owned as of the balance sheet date.No definition available.false256Number of rental units7false 4us-gaap_MortgageLoansOnRealEstateCarryingAmountOfMortgagesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6truefalsefalse4360000043600000falsefalsefalse7falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe carrying amount of the outstanding balance due under the mortgage loan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule IV) -URI http://asc.fasb.org/extlink&oid=6882300&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 29 -Article 12 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph c -Subparagraph Schedule IV -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29) -URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014 false2Mortgage loan carrying amount8false 4cli_ThresholdOfWhichExcessProceedsArePaidToThirdPartycli_falsecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6truefalsefalse4700000047000000USD$falsetruefalse7falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThreshold Of Which Excess Proceeds Are Paid To Third PartyNo definition available.false2Threshold of which excess proceeds are paid to another party9false 4us-gaap_DebtInstrumentBasisSpreadOnVariableRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalse1truetruefalse0.01250.0125falsefalsefalse2falsetruefalse00falsefalsefalse3falsetruefalse00falsefalsefalse4falsetruefalse00falsefalsefalse5falsetruefalse00falsefalsefalse6truetruefalse0.03250.0325falsefalsefalse7falsetruefalse00falsefalsefalsenum:percentItemTypepureThe percentage points added to the reference rate to compute the variable rate on the debt instrument.No definition available.false0Spread over LIBOR10false 4us-gaap_MortgageLoanOnRealEstateFinalMaturityDateus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse002013-08-01falsefalsetrue7falsefalsefalse00falsefalsefalsexbrli:dateItemTypedateStated maturity date of the mortgage loan receivable on real estate, in CCYY-MM-DD format.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 10 -Section S99 -Paragraph 6 -Subparagraph (SX 210.5-04.(c) Schedule IV) -URI http://asc.fasb.org/extlink&oid=6882300&loc=d3e5864-122674 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 29 -Article 12 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph c -Subparagraph Schedule IV -Article 5 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 948 -SubTopic 310 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-29) -URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014 false0Mortgage loan scheduled to mature11false 4cli_DebtInstrumentExtensionPeriodcli_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse001 yearfalsefalsefalse7falsefalsefalse00falsefalsefalsexbrli:durationItemTypenaDebt Instrument Extension PeriodNo definition available.false0Loan extension period12false 4us-gaap_EquityMethodInvestmentOwnershipPercentageus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsetruefalse00falsefalsefalse2falsetruefalse00falsefalsefalse3falsetruefalse00falsefalsefalse4falsetruefalse00falsefalsefalse5truetruefalse0.800.80falsefalsefalse6falsetruefalse00falsefalsefalse7falsetruefalse00falsefalsefalsenum:percentItemTypepureThe percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 159 -Paragraph 18 -Subparagraph f -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 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 20 -Subparagraph a (1) -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. false0Percentage of interest in venture13false 4cli_ThirdPartyOwnershipPercentcli_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsetruefalse00falsefalsefalse2falsetruefalse00falsefalsefalse3falsetruefalse00falsefalsefalse4falsetruefalse00falsefalsefalse5truetruefalse0.200.20falsefalsefalse6falsetruefalse00falsefalsefalse7falsetruefalse00falsefalsefalsenum:percentItemTypepureThird Party Ownership PercentNo definition available.false0Third party ownership percentage14false 4cli_HoldingAndDistributionPatternUnderOperatingAgreementcli_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00The operating agreement of Stamford SM provides, among other things, for distributions of net available cash in accordance with its members' respective ownership percentages. The Company holds an 80 percent interest in the venture. The Company and the 20 percent member share equally in decision-making on all major decisions involving the operations of the venture.falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringHolding And Distribution Pattern Under Operating AgreementNo definition available.false0Holding and distribution pattern under operating agreementfalseInvestments In Unconsolidated Joint Ventures (Stamford SM LLC) (Narrative) (Details) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.mack-cali.com/role/DisclosureInvestmentsInUnconsolidatedJointVenturesStamfordSmLlcNarrativeDetails714