Annual report pursuant to Section 13 and 15(d)

Mortgages, Loans Payable And Other Obligations (Narrative) (Details)

v2.4.1.9
Mortgages, Loans Payable And Other Obligations (Narrative) (Details) (USD $)
12 Months Ended
Dec. 31, 2014
property
Dec. 31, 2013
Dec. 31, 2012
Debt Instrument [Line Items]      
Number of properties with encumbered company mortgages 30cli_NumberOfPropertiesWithEncumberedCompanyMortgages    
Book value of encumbered properties $ 998,000,000cli_MortgagePropertyCarryingValue    
Cash paid for interest 119,664,000us-gaap_InterestPaid 123,213,000us-gaap_InterestPaid 120,089,000us-gaap_InterestPaid
Interest capitalized 15,470,000us-gaap_InterestCostsCapitalized 12,885,000us-gaap_InterestCostsCapitalized 4,342,000us-gaap_InterestCostsCapitalized
Total indebtedness 2,088,654,000us-gaap_LongTermDebt 2,362,766,000us-gaap_LongTermDebt  
Total indebtedness, weighted average interest rate 5.64%us-gaap_LongtermDebtWeightedAverageInterestRate 5.62%us-gaap_LongtermDebtWeightedAverageInterestRate  
Revolving Credit Facility Borrowing And Other Variable Rate Mortgage Debt [Member]      
Debt Instrument [Line Items]      
Total indebtedness 159,860,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember
80,228,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember
 
Total indebtedness, weighted average interest rate 3.83%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember
2.74%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_RevolvingCreditFacilityAndOtherVariableRateMortgageDebtMember
 
Fixed Rate Debt And Other Obligations [Member]      
Debt Instrument [Line Items]      
Total indebtedness 1,928,794,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember
2,282,538,000us-gaap_LongTermDebt
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember
 
Total indebtedness, weighted average interest rate 5.79%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember
5.72%us-gaap_LongtermDebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= cli_FixedRateDebtAndOtherObligationsMember
 
Unconsolidated Joint Venture [Member]      
Debt Instrument [Line Items]      
Interest capitalized $ 4,646,000us-gaap_InterestCostsCapitalized
/ dei_LegalEntityAxis
= us-gaap_CorporateJointVentureMember
$ 1,326,000us-gaap_InterestCostsCapitalized
/ dei_LegalEntityAxis
= us-gaap_CorporateJointVentureMember
$ 235,000us-gaap_InterestCostsCapitalized
/ dei_LegalEntityAxis
= us-gaap_CorporateJointVentureMember