Description of Business and Basis of Presentation - Description of Business (Details) ft² in Thousands	9 Months Ended
	Sep. 30, 2021 ft²
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Distribution of taxable income to qualify as REIT, percentage	100.00%
Portfolio of real estate assets, office space area	18,500
Portfolio of real estate assets, retail space area	620
CPLP
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Percentage of partnership units owned by the Company (more than)	99.00%