Organization (Details) - 3 months ended Mar. 31, 2024 ft² in Thousands	property	ft²	a	shares
COPT Defense Properties | Preferred Units
Investments in real estate
Limited partners' capital account, units outstanding (in units) | shares				0
COPT Defense Properties, L.P. | COPT Defense Properties | Common Units | COPT Defense Properties
Investments in real estate
Percentage ownership in operating partnership	97.50%
Unconsolidated Real Estate Joint Ventures
Investments in real estate
Number of real estate properties	24
Operating Properties | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	193
Area of real estate property (in sqft or acres) | ft²		22,000
Operating Properties | Greater Washington, DC/Baltimore | Other
Investments in real estate
Number of real estate properties	8
Area of real estate property (in sqft or acres) | ft²		2,100
Operating Properties | Office Properties | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	163
Area of real estate property (in sqft or acres) | ft²		16,300
Operating Properties | Single-tenant data centers | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	30
Area of real estate property (in sqft or acres) | ft²		5,700
Operating Properties | Single-tenant data centers | Unconsolidated Real Estate Joint Ventures | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	24
Properties under development | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	6
Area of real estate property (in sqft or acres) | ft²		959
Properties under development | Office Properties | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	3
Properties under development | Single-tenant data centers | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	3
Properties under development, partially operational | Defense/IT Portfolio
Investments in real estate
Number of real estate properties	1
Land controlled for development | Defense/IT Portfolio
Investments in real estate
Area of real estate property (in sqft or acres)		7,700	650
Land controlled for development | Greater Washington, DC/Baltimore | Other
Investments in real estate
Area of real estate property (in sqft or acres) | a			50