Share-Based Compensation (Tables)  | 
6 Months Ended | |||||||||||||||||||||
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Jun. 30, 2019  | ||||||||||||||||||||||
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | ||||||||||||||||||||||
| Schedule of payouts for defined performance under performance-based awards of share-based compensation | The number of earned awards at the end of the performance period will be determined based on the percentile rank of COPT’s total shareholder return relative to a peer group of companies, as set forth in the following schedule:
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- Definition Schedule of payouts for defined performance under performance-based awards of share-based compensation No definition available. 
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- References No definition available. 
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