Commitments and Contingencies (Details) $ in Thousands  | 
 Jun. 30, 2019  
USD ($)  
property 
 | 
 Dec. 31, 2018  
USD ($) 
 | 
|---|---|---|
| Environmental Indemnity Agreement | ||
| Number of properties which were provided environmental indemnifications | property | 3 | |
| Maximum additional costs agreed to be paid by the entity under environmental indemnification agreement | $ 19,000 | |
| Carrying Value | 1,784,362 | $ 1,823,909 | 
| Development and Redevelopment Obligations | ||
| Environmental Indemnity Agreement | ||
| Purchase obligations | 174,000 | |
| Tenant and Other Capital Improvements | ||
| Environmental Indemnity Agreement | ||
| Purchase obligations | 51,800 | |
| Third Party Construction | ||
| Environmental Indemnity Agreement | ||
| Purchase obligations | 15,400 | |
| Other Obligations | ||
| Environmental Indemnity Agreement | ||
| Purchase obligations | 1,700 | |
| Specialty Tax Guarantee | Anne Arundel County, Maryland | Tax Incremental Financing Bond | ||
| Environmental Indemnity Agreement | ||
| Carrying Value | $ 35,000 | 
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- References No definition available. 
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- Definition Maximum additional costs agreed to be paid by the entity under environmental indemnification agreement No definition available. 
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- Definition Represents the number of properties in New Jersey which were provided environmental indemnifications by the entity. No definition available. 
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- Definition Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments. No definition available. 
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- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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