Annual report pursuant to Section 13 and 15(d)

Investments In Unconsolidated Joint Ventures (Summary Of Company's Investment In Unconsolidated Joint Ventures) (Details)

v2.4.1.9
Investments In Unconsolidated Joint Ventures (Summary Of Company's Investment In Unconsolidated Joint Ventures) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Dec. 23, 2013
May 21, 2014
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net $ 247,468us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures $ 181,129us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures    
Accounts payable, accrued expenses and other liabilities 126,971us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent 121,286us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent    
Marbella RoseGarden, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 15,779us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_MarbellaRoseGardenLLCMember 		15,797us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_MarbellaRoseGardenLLCMember 		   
RoseGarden Monaco Holdings, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 2,161us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMonacoHoldingsLLCMember 		3,201us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMonacoHoldingsLLCMember 		   
Rosewood Lafayette Holdings, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 62us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodLafayetteHoldingsLLCMember 		857us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodLafayetteHoldingsLLCMember 		   
Rosewood Morristown, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 6,029us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodMorristownLLCMember 		[1],[2] 6,455us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodMorristownLLCMember 		[1],[2]    
Overlook Ridge JV 2C/3B, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 2,524us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OverlookRidgeJvTwoCAndThreeBLLCMember 		[3]      
PruRose Riverwalk G, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 955us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRoseRiverwalkGLLCMember 		[4] 3,117us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRoseRiverwalkGLLCMember 		[4]    
Elmajo Urban Renewal Associates, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net   203us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_ElmajoUrbanRenewalAssociatesLLCMember 		[4]    
Crystal House Apartments Investors LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 27,051us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		[5] 26,838us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember 		[5]    
Portside Master Company, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 1,747us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PortsideMasterCompanyLLCMember 		3,207us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PortsideMasterCompanyLLCMember 		   
PruRose Port Imperial South 13, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 1,087us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRosePortImperialSouthThirteenLLCMember 		2,206us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRosePortImperialSouthThirteenLLCMember 		   
Roseland/Port Imperial Partners, L.P. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 1,800us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandPortImperialPartnersLPMember 		[4],[6] 2,068us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandPortImperialPartnersLPMember 		[4],[6]    
RoseGarden Marbella South, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 11,282us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMarbellaSouthLLCMember 		7,567us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMarbellaSouthLLCMember 		   
Estuary Urban Renewal Unit B, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net   24us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_EstuaryUrbanRenewalUnitBLLCMember 		   
RiverPark At Harrison I, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 4,744us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RiverparkAtHarrisonILLCMember 		3,655us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RiverparkAtHarrisonILLCMember 		   
Capitol Place Mezz LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 49,327us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CapitolPlaceMezzLlcMember 		46,628us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CapitolPlaceMezzLlcMember 		46,500us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CapitolPlaceMezzLlcMember 		 
Harborside Unit A Urban Renewal, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 34,954us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_HarborsideUnitaUrbanRenewalLLCMember 		    30,600us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_HarborsideUnitaUrbanRenewalLLCMember
RoseGarden Monaco, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 1,283us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMonacoLLCMember 		1,224us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMonacoLLCMember 		   
Grand Jersey Waterfront Urban Renewal Associates, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 337us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_GrandJerseyWaterfrontUrbanRenewalAssociatesLLCMember 		337us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_GrandJerseyWaterfrontUrbanRenewalAssociatesLLCMember 		   
Red Bank Corporate Plaza, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 3,963us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RedBankCorporatePlazaLLCMember 		4,046us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RedBankCorporatePlazaLLCMember 		   
12 Vreeland Associates, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 5,620us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_TwelveVreelandAssociatesLLCMember 		5,514us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_TwelveVreelandAssociatesLLCMember 		   
BNES Associates III [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 1,993us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_BNESAssociatesIIIMember 		1,753us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_BNESAssociatesIIIMember 		   
Hillsborough 206 Holdings, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 1,962us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_HillsboroughTwoHundredSixHoldingsLLCMember 		1,962us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_HillsboroughTwoHundredSixHoldingsLLCMember 		   
KPG-P 100 IMW JV, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net   1,887us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_KpgPOneHundredImwJvLlcMember 		   
Keystone-TriState [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 6,140us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_KeystoneTristateMember 		     
KPG-MCG Curtis JV, LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 59,911us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_KpgMcgCurtisJvLLCMember 		[7]      
Plaza VIII & IX Associates, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 4,022us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PlazaEightAndNineAssociatesLLCMember 		3,702us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PlazaEightAndNineAssociatesLLCMember 		   
Roseland/North Retail, L.L.C. [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net 1,828us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandNorthRetailLLCMember 		[4] 1,930us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandNorthRetailLLCMember 		[4]    
South Pier At Harborside [Member]        
Schedule of Equity Method Investments [Line Items]        
Accounts payable, accrued expenses and other liabilities 1,854us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_SouthPierAtHarborsideMember 		1,706us-gaap_AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_SouthPierAtHarborsideMember 		   
Stamford SM LLC [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net   36,258us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_StamfordSmLlcMember 		[8]    
Other [Member]        
Schedule of Equity Method Investments [Line Items]        
Company's investments in unconsolidated joint ventures, net $ 907us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OtherJointVenturesMember 		[9] $ 693us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OtherJointVenturesMember 		[9]    
[1] Through the joint venture, the Company also owns a 12.5 percent interest in a 50,973 square feet retail building ("Shops at 40 Park") and a 25 percent interest in a to-be-built 59-unit, five story multi-family rental development property ("Lofts at 40 Park").
[2] The Company's ownership interests in this venture are subordinate to its partner's preferred capital balance and the payment of the outstanding balance remaining on a note ($975 as of December 31, 2014), and is not expected to meaningfully participate in the venture's cash flows in the near term.
[3] On August 15, 2014, the Company acquired the equity interests of its joint venture partner in Overlook Ridge JV 2C/3B, L.L.C. for $2.97 million and LR Overlook Phase II, L.L.C., the property-owning entity owned by Overlook Ridge JV, L.L.C., which increased its ownership to 50 percent in two operating multi-family properties. The Company also acquired the equity interests of its joint venture partner in LR Overlook Phase III, L.L.C. and Overlook Ridge, L.L.C. for $0.6 million and $12.99 million respectively, which increased its ownership to 100 percent in developable land (See Note 3: Real Estate Transactions - Acquisitions).
[4] The Company's ownership interests in this venture are subordinate to its partner's preferred capital balance and the Company is not expected to meaningfully participate in the venture's cash flows in the near term.
[5] The Company also owns a 50 percent interest in a vacant land parcel to accommodate the development of approximately 295 additional units of which 252 are currently approved.
[6] The Company also owns a 20 percent residual interest in undeveloped land parcels: parcels 6, I, and J ("Port Imperial North Land") that can accommodate the development of 836 apartment units.
[7] Includes undivided interests in the same manner as investments in noncontrolling partnership, pursuant to ASC 970-323-25-12. See discussion in Unconsolidated Joint Venture Transactions following in this footnote.
[8] The joint venture collected net proceeds of $47.2 million at maturity, of which the Company received its share of $37.8 million on August 6, 2014.
[9] The Company owns other interests in various unconsolidated joint ventures, including interests in assets previously owned and interest in ventures whose businesses are related to its core operations. These ventures are not expected to significantly impact the Company's operations in the near term.