COPT Defense Properties Quarterly report pursuant to Section 13 or 15(d)

Interest Rate Derivatives - Key Terms and Fair Value of Interest Rate Derivative (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Fair values of interest rate swap derivatives
Fair value of interest rate swaps	$ 1,824	$ 2,631
Designated \| Interest rate swap, effective August 1, 2019
Fair values of interest rate swap derivatives
Notional Amount	$ 10,820
Fixed Rate	1.678%
Fair value of interest rate swaps	$ 654	806
Notional amount of interest rate derivatives after scheduled amortization	$ 10,000
Designated \| Interest rate swap, effective August 1, 2019 \| Secured Overnight Financing Rate
Fair values of interest rate swap derivatives
Floating Rate Index	0.10%
Designated \| Interest rate swap, effective April 1, 2020
Fair values of interest rate swap derivatives
Notional Amount	$ 22,700
Fixed Rate	0.573%
Fair value of interest rate swaps	$ 1,525	1,825
Notional amount of interest rate derivatives after scheduled amortization	$ 22,100
Designated \| Interest rate swap, effective April 1, 2020 \| Secured Overnight Financing Rate
Fair values of interest rate swap derivatives
Floating Rate Index	0.10%
Designated \| Interest Rate Swap, Effective February 1, 2023 3.742%
Fair values of interest rate swap derivatives
Notional Amount	$ 150,000
Fixed Rate	3.742%
Fair value of interest rate swaps	$ (262)	0
Designated \| Interest Rate Swap, Effective February 1, 2023 3.747%
Fair values of interest rate swap derivatives
Notional Amount	$ 50,000
Fixed Rate	3.747%
Fair value of interest rate swaps	$ (93)	$ 0