Quarterly report pursuant to Section 13 or 15(d)

Employee Benefit 401(k) Plans And Deferred Retirement Compensation Agreements (Details)

v2.4.1.9
Employee Benefit 401(k) Plans And Deferred Retirement Compensation Agreements (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Minimum employee subscription rate, percentage of compensation 1.00%cli_SavingsRetirementPlanEmployeeMinimumSubscriptionRate  
Maximum employee subscription rate, percentage of compensation 60.00%cli_SavingsRetirementPlanEmployeeMaximumSubscriptionRate  
Employee pre-tax contributions vested percentage 100.00%cli_EmployeePreTaxContributionsVestedPercent  
Vesting rate 20.00%cli_VestingRate  
Percentage vested after total service period 100.00%cli_PercentVestedAfterTotalServicePeriod  
Employees' vesting rights Participants are always 100 percent vested in their pre-tax contributions and will begin vesting in any matching or profit sharing contributions made on their behalf after two years of service with the Company at a rate of 20 percent per year, becoming 100 percent vested after a total of six years of service with the Company.  
Expenses for employee benefit plan $ 0us-gaap_EmployeeBenefitsAndShareBasedCompensation $ 25,000us-gaap_EmployeeBenefitsAndShareBasedCompensation
Minimum [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Employer contribution vesting period 2 years  
Maximum [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Employer contribution vesting period 6 years  
Messr Lefkowitz And Messr Thomas [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Expenses for employee benefit plan 1,200,000us-gaap_EmployeeBenefitsAndShareBasedCompensation
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurLefkowitzAndMessieurThomasMember
 
Messr Hersh [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Expenses for employee benefit plan 2,300,000us-gaap_EmployeeBenefitsAndShareBasedCompensation
/ us-gaap_TitleOfIndividualAxis
= cli_MessieurHershMember
 
Deferred Retirement Compensation Units [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Expenses for employee benefit plan $ 0us-gaap_EmployeeBenefitsAndShareBasedCompensation
/ us-gaap_AwardTypeAxis
= cli_DeferredRetirementCompensationUnitsMember
$ 1,200,000us-gaap_EmployeeBenefitsAndShareBasedCompensation
/ us-gaap_AwardTypeAxis
= cli_DeferredRetirementCompensationUnitsMember