Annual report pursuant to Section 13 and 15(d)

Investments In Unconsolidated Joint Ventures (Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures) (Details)

v2.4.1.9
Investments In Unconsolidated Joint Ventures (Summary Of Company's Equity In Earnings (Loss) Of Unconsolidated Joint Ventures) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures $ (363)us-gaap_IncomeLossFromEquityMethodInvestments $ (1,268)us-gaap_IncomeLossFromEquityMethodInvestments $ 443us-gaap_IncomeLossFromEquityMethodInvestments $ (1,235)us-gaap_IncomeLossFromEquityMethodInvestments $ (268)us-gaap_IncomeLossFromEquityMethodInvestments $ (229)us-gaap_IncomeLossFromEquityMethodInvestments $ (80)us-gaap_IncomeLossFromEquityMethodInvestments $ (1,750)us-gaap_IncomeLossFromEquityMethodInvestments $ (2,423)us-gaap_IncomeLossFromEquityMethodInvestments $ (2,327)us-gaap_IncomeLossFromEquityMethodInvestments $ 4,089us-gaap_IncomeLossFromEquityMethodInvestments
Marbella RoseGarden, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (19)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_MarbellaRoseGardenLLCMember
(540)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_MarbellaRoseGardenLLCMember
13us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_MarbellaRoseGardenLLCMember
RoseGarden Monaco, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (1,040)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMonacoLLCMember
(1,560)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMonacoLLCMember
(311)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMonacoLLCMember
Rosewood Lafayette Holdings, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (853)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodLafayetteHoldingsLLCMember
(1,131)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodLafayetteHoldingsLLCMember
(197)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodLafayetteHoldingsLLCMember
PruRose Port Imperial South 15, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                   (606)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRosePortImperialSouthFifteenLLCMember
(533)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRosePortImperialSouthFifteenLLCMember
Rosewood Morristown, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (345)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodMorristownLLCMember
(509)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodMorristownLLCMember
(25)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RosewoodMorristownLLCMember
Overlook Ridge JV 2C/3B, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (384)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OverlookRidgeJvTwoCAndThreeBLLCMember
293us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OverlookRidgeJvTwoCAndThreeBLLCMember
(11)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OverlookRidgeJvTwoCAndThreeBLLCMember
PruRose Riverwalk G, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (2,139)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRoseRiverwalkGLLCMember
(985)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRoseRiverwalkGLLCMember
(142)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRoseRiverwalkGLLCMember
Elmajo Urban Renewal Associates, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (203)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_ElmajoUrbanRenewalAssociatesLLCMember
(345)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_ElmajoUrbanRenewalAssociatesLLCMember
(83)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_ElmajoUrbanRenewalAssociatesLLCMember
Crystal House Apartments Investors LLC [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (139)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember
(2,639)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CrystalHouseApartmentsInvestorsLLCMember
 
Portside Master Company, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (1,163)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PortsideMasterCompanyLLCMember
(421)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PortsideMasterCompanyLLCMember
(5)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PortsideMasterCompanyLLCMember
PruRose Port Imperial South 13, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (863)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRosePortImperialSouthThirteenLLCMember
(664)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRosePortImperialSouthThirteenLLCMember
(87)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PruRosePortImperialSouthThirteenLLCMember
Roseland/Port Imperial Partners, L.P. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (646)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandPortImperialPartnersLPMember
(740)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandPortImperialPartnersLPMember
 
RoseGarden Marbella South, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                   (57)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMarbellaSouthLLCMember
(13)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoseGardenMarbellaSouthLLCMember
Estuary Urban Renewal Unit B, LLC [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (15)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_EstuaryUrbanRenewalUnitBLLCMember
(157)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_EstuaryUrbanRenewalUnitBLLCMember
 
RiverPark At Harrison I, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (150)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RiverparkAtHarrisonILLCMember
   
Capitol Place Mezz LLC [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (75)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_CapitolPlaceMezzLlcMember
   
Harborside Unit A Urban Renewal, LLC [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (218)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_HarborsideUnitaUrbanRenewalLLCMember
   
Grand Jersey Waterfront Urban Renewal Associates, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (54)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_GrandJerseyWaterfrontUrbanRenewalAssociatesLLCMember
(77)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_GrandJerseyWaterfrontUrbanRenewalAssociatesLLCMember
 
Red Bank Corporate Plaza, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 380us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RedBankCorporatePlazaLLCMember
372us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RedBankCorporatePlazaLLCMember
360us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RedBankCorporatePlazaLLCMember
12 Vreeland Associates, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 106us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_TwelveVreelandAssociatesLLCMember
74us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_TwelveVreelandAssociatesLLCMember
427us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_TwelveVreelandAssociatesLLCMember
BNES Associates III [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 240us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_BNESAssociatesIIIMember
(14)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_BNESAssociatesIIIMember
(323)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_BNESAssociatesIIIMember
Hillsborough 206 Holdings, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (10)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_HillsboroughTwoHundredSixHoldingsLLCMember
(35)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_HillsboroughTwoHundredSixHoldingsLLCMember
 
KPG-P 100 IMW JV, LLC [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (1,887)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_KpgPOneHundredImwJvLlcMember
(913)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_KpgPOneHundredImwJvLlcMember
 
Keystone-TriState [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (318)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_KeystoneTristateMember
   
KPG-MCG Curtis JV, LLC [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 624us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_KpgMcgCurtisJvLLCMember
   
Plaza VIII & IX Associates, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 320us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PlazaEightAndNineAssociatesLLCMember
99us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PlazaEightAndNineAssociatesLLCMember
30us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_PlazaEightAndNineAssociatesLLCMember
Roseland/North Retail, L.L.C. [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 (102)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandNorthRetailLLCMember
(230)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandNorthRetailLLCMember
(80)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_RoselandNorthRetailLLCMember
South Pier At Harborside [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 2,602us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_SouthPierAtHarborsideMember
2,519us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_SouthPierAtHarborsideMember
2,368us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_SouthPierAtHarborsideMember
Stamford SM LLC [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 2,337us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_StamfordSmLlcMember
3,719us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_StamfordSmLlcMember
3,078us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_StamfordSmLlcMember
Other [Member]                      
Schedule of Equity Method Investments [Line Items]                      
Company's equity in earnings (loss) of unconsolidated joint ventures                 $ 1,591us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OtherJointVenturesMember
$ 2,220us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OtherJointVenturesMember
$ (377)us-gaap_IncomeLossFromEquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= cli_OtherJointVenturesMember