Annual report pursuant to Section 13 and 15(d)

Unsecured Revolving Credit Facility (Change In The Operating Partnership's Unsecured Debt Ratings) (Details)

v2.4.1.9
Unsecured Revolving Credit Facility (Change In The Operating Partnership's Unsecured Debt Ratings) (Details) (Unsecured Revolving Credit Facility [Member])
12 Months Ended
Dec. 31, 2014
No Ratings Or Less Than Baa3 [Member] | No Ratings Or Less Than BBB- [Member]
 
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings No ratings or less than BBB-/Baa3
Interest Rate - Applicable Basis Points Above LIBOR 1.70%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= cli_NoRatingsOrLessThanMoodysBaa3RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= cli_NoRatingsOrLessThanStandardPoorsBBBMinusMember
Facility Fee Basis Points 0.35%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= cli_NoRatingsOrLessThanMoodysBaa3RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= cli_NoRatingsOrLessThanStandardPoorsBBBMinusMember
Baa3 [Member] | BBB- [Member]
 
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings BBB- or Baa3 (current)
Interest Rate - Applicable Basis Points Above LIBOR 1.30%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= us-gaap_MoodysBaa3RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= us-gaap_StandardPoorsBBBMinusRatingMember
Facility Fee Basis Points 0.30%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= us-gaap_MoodysBaa3RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= us-gaap_StandardPoorsBBBMinusRatingMember
Baa2 [Member] | BBB [Member]
 
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings BBB or Baa2
Interest Rate - Applicable Basis Points Above LIBOR 1.10%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= us-gaap_MoodysBaa2RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= us-gaap_StandardPoorsBBBRatingMember
Facility Fee Basis Points 0.20%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= us-gaap_MoodysBaa2RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= us-gaap_StandardPoorsBBBRatingMember
Baa1 [Member] | BBB+ [Member]
 
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings BBB+ or Baa1
Interest Rate - Applicable Basis Points Above LIBOR 1.00%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= us-gaap_MoodysBaa1RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= us-gaap_StandardPoorsBBBPlusRatingMember
Facility Fee Basis Points 0.15%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= us-gaap_MoodysBaa1RatingMember
/ us-gaap_CreditRatingStandardPoorsAxis
= us-gaap_StandardPoorsBBBPlusRatingMember
A3 Or Higher [Member] | A- Or Higher [Member]
 
Line of Credit Facility [Line Items]  
Unsecured Debt Ratings A- or A3 or higher
Interest Rate - Applicable Basis Points Above LIBOR 0.925%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= cli_MoodysA3RatingOrHigherMember
/ us-gaap_CreditRatingStandardPoorsAxis
= cli_StandardPoorsMinusRatingOrHigherMember
Facility Fee Basis Points 0.125%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ us-gaap_CreditFacilityAxis
= us-gaap_RevolvingCreditFacilityMember
/ us-gaap_CreditRatingMoodysAxis
= cli_MoodysA3RatingOrHigherMember
/ us-gaap_CreditRatingStandardPoorsAxis
= cli_StandardPoorsMinusRatingOrHigherMember