2.4.0.840703 - Disclosure - Discontinued Operations (Schedule Of Properties Identified As Held For Sale) (Details)truefalseIn Thousands, unless otherwise specifiedfalse1false USDfalsefalse$Duration_1_1_2013_To_6_30_2013http://www.sec.gov/CIK0000924901duration2013-01-01T00:00:002013-06-30T00:00:00Unit1Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$As_Of_12_31_2012http://www.sec.gov/CIK0000924901instant2012-12-31T00:00:000001-01-01T00:00:00Unit1Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDtruefalse$Duration_7_9_2013_To_7_10_2013_us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis_cli_OneHunderedSixAllenRoadMemberhttp://www.sec.gov/CIK0000924901duration2013-07-09T00:00:002013-07-10T00:00:00falsefalse106 Allen Road [Member]us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxisxbrldihttp://xbrl.org/2006/xbrldicli_OneHunderedSixAllenRoadMemberus-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxisexplicitMemberUnit1Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4false USDtruefalse$As_Of_6_30_2013_us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis_cli_OneHunderedSixAllenRoadMemberhttp://www.sec.gov/CIK0000924901instant2013-06-30T00:00:000001-01-01T00:00:00falsefalse106 Allen Road [Member]us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxisxbrldihttp://xbrl.org/2006/xbrldicli_OneHunderedSixAllenRoadMemberus-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxisexplicitMemberUnit17Standardhttp://www.mack-cali.com/20130630itemcli0Unit12Standardhttp://www.xbrl.org/2009/utrsqftutr0Unit1Standardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_LongLivedAssetsHeldForSaleLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Long Lived Assets Held-for-sale [Line Items]2false 4cli_NumberOfBuildingsHeldForSalecli_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse11[1]falsefalsefalsexbrli:integerItemTypeintegerNumber Of Buildings Held For SaleNo definition available.false256Number of Buildings3false 4cli_AreaOfRealEstatePropertyHeldForSalecli_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse132010132010[1]falsefalsefalsenum:areaItemTypedecimalArea Of Real Estate Property Held For SaleNo definition available.false256Rentable Square Feet4false 4cli_AssetsHeldForSalePropertyPlantAndEquipmentGrosscli_falsedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse1789500017895[1]USD$falsetruefalsexbrli:monetaryItemTypemonetaryAssets Held For Sale, Property Plant And Equipment, GrossNo definition available.false2Gross Book Value5false 4cli_AssetsHeldForSalePropertyPlantAndEquipmentAccumulatedDepreciationcli_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsetruenegatedLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse-5044000-5044[1]falsefalsefalsexbrli:monetaryItemTypemonetaryAssets Held For Sale, Property Plant And Equipment, Accumulated DepreciationNo definition available.false2Accumulated Depreciation6false 4us-gaap_AssetsHeldForSalePropertyPlantAndEquipmentus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse1285100012851falsefalsefalse2truefalsefalse6086300060863falsefalsefalse3falsefalsefalse00falsefalsefalse4truefalsefalse1285100012851[1]falsefalsefalsexbrli:monetaryItemTypemonetaryProperty, plant and equipment that is held for sale apart from normal operations and anticipated to be sold in less than one year.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 45 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1107-107759 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 46 -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. true2Net Book Value7false 4us-gaap_ProceedsFromSaleOfRealEstateHeldforinvestmentus-gaap_truedebitdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse165513000165513USD$falsetruefalse2falsefalsefalse00falsefalsefalse3truefalsefalse1800000018000USD$falsetruefalse4falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryCash received from the sale of real estate that is held for investment, that is, it is part of an investing activity during the period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -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 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3179-108585 false2Sales proceeds1On July 10, 2013, the Company sold this property for approximately $18.0 million.falseDiscontinued Operations (Schedule Of Properties Identified As Held For Sale) (Details) (USD $)ThousandsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.mack-cali.com/role/DisclosureDiscontinuedOperationsScheduleOfPropertiesIdentifiedAsHeldForSaleDetails47