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Share and Unit-Based Plans - Narrative (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
3 Months Ended 0 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Mar. 06, 2015
Jan. 01, 2015
Share and unit-based plans        
Capitalized share and unit-based compensation costs $ 4,347us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount $ 3,841us-gaap_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsCapitalizedAmount    
Stock units        
Share and unit-based plans        
Conversion rate of shares 1mac_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsConversionRate
/ us-gaap_AwardTypeAxis
= mac_StockUnitsMember
     
Granted (in shares) 75,171us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= mac_StockUnitsMember
     
Average grant date fair value (in dollars per share) $ 86.72us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= mac_StockUnitsMember
     
Unrecognized compensation cost of share and unit-based plans 6,107us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= mac_StockUnitsMember
     
LTIP Units        
Share and unit-based plans        
Conversion rate of shares 1mac_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherthanOptionsConversionRate
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
     
Granted (in shares) 368,508us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
     
Average grant date fair value (in dollars per share) $ 75.98us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
     
Share-based Compensation Arrangement by Share-based Payment Award Equity Instruments other than Options, Absolute Return Requirement 3.00%mac_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsotherthanOptionsAbsoluteReturnRequirement
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
     
Unrecognized compensation cost of share and unit-based plans 15,522us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
     
Stock awards        
Share and unit-based plans        
Granted (in shares) 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= mac_StockAwardsMember
     
Average grant date fair value (in dollars per share) $ 0.00us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= mac_StockAwardsMember
     
Unrecognized compensation cost of share and unit-based plans 174us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= mac_StockAwardsMember
     
Stock options        
Share and unit-based plans        
Unrecognized compensation cost of share and unit-based plans 39us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Phantom stock units        
Share and unit-based plans        
Granted (in shares) 3,185us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_PhantomShareUnitsPSUsMember
     
Average grant date fair value (in dollars per share) $ 84.97us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_PhantomShareUnitsPSUsMember
     
Unrecognized compensation cost of share and unit-based plans $ 500us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_PhantomShareUnitsPSUsMember
     
Executive Officer | LTIP Units        
Share and unit-based plans        
Average grant date fair value (in dollars per share)     $ 86.72us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
 
2016 LTIP Units Series 1 | Executive Officer | LTIP Units        
Share and unit-based plans        
Granted (in shares)       49,451us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
/ us-gaap_PlanNameAxis
= mac_A2015LTIPUnitsSeries1Member
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
Average grant date fair value (in dollars per share)       $ 83.41us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
/ us-gaap_PlanNameAxis
= mac_A2015LTIPUnitsSeries1Member
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
2015 LTIP Units Series 2 [Member] | Executive Officer | LTIP Units        
Share and unit-based plans        
Granted (in shares)       186,450us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
/ us-gaap_PlanNameAxis
= mac_A2015LTIPUnitsSeries2Member
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
Average grant date fair value (in dollars per share)       $ 66.37us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
/ us-gaap_PlanNameAxis
= mac_A2015LTIPUnitsSeries2Member
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember
2015 LTIP Units Series 3 | Executive Officer | LTIP Units        
Share and unit-based plans        
Granted (in shares)     132,607us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= mac_LongTermIncentivePlanMember
/ us-gaap_PlanNameAxis
= mac_A2015LTIPUnitsSeries3Member
/ us-gaap_TitleOfIndividualAxis
= us-gaap_ExecutiveOfficerMember