COPT Defense Properties Quarterly report [Sections 13 or 15(d)]

Quarterly report [Sections 13 or 15(d)]

Debt, Net - Components of Debt (Details)

Debt, Net - Components of Debt (Details)		9 Months Ended
Debt, Net - Components of Debt (Details)	Sep. 30, 2025 USD ($) extension $ / shares	Sep. 30, 2025 USD ($) extension $ / shares	Dec. 31, 2024 USD ($)
Debt
Carrying Value	$ 2,443,518,000	$ 2,443,518,000	$ 2,391,755,000
Net deferred financing costs	3,000,000.0	3,000,000.0	4,000,000.0
Mortgage and Other Secured Debt
Debt
Carrying Value	$ 68,456,000	$ 68,456,000	69,601,000
Fixed-rate mortgage debt \| Mortgage and Other Secured Debt
Debt
Interest rate	3.82%	3.82%
Carrying Value	$ 36,336,000	$ 36,336,000	37,130,000
Variable-rate secured debt \| Mortgage and Other Secured Debt
Debt
Carrying Value	$ 32,120,000	$ 32,120,000	32,471,000
Variable rate, additional spread over SOFR		0.10%
Weighted average interest rate	5.95%	5.95%
Extension option period		12 months
Extension fee percentage		0.10%
Variable-rate secured debt \| Mortgage and Other Secured Debt \| Interest rate swaps
Debt
Weighted average interest rate	5.14%	5.14%
Variable-rate secured debt \| Mortgage and Other Secured Debt \| Minimum
Debt
Variable rate, spread over SOFR		1.45%
Variable-rate secured debt \| Mortgage and Other Secured Debt \| Maximum
Debt
Variable rate, spread over SOFR		1.55%
Credit Agreement \| Line of Credit \| Revolving Credit Facility
Debt
Carrying Value	$ 124,000,000	$ 124,000,000	75,000,000
Variable rate, additional spread over SOFR		0.10%
Weighted average interest rate	5.37%	5.37%
Extension option period		6 months
Extension fee percentage		0.0625%
Number of extensions \| extension	2	2
Credit Agreement \| Line of Credit \| Revolving Credit Facility \| Minimum
Debt
Variable rate, spread over SOFR		0.725%
Credit Agreement \| Line of Credit \| Revolving Credit Facility \| Maximum
Debt
Variable rate, spread over SOFR		1.40%
Credit Agreement \| Term Loan Facility \| Term Loan Facility
Debt
Interest rate	5.68%	5.68%
Carrying Value	$ 124,891,000	$ 124,891,000	124,633,000
Variable rate, additional spread over SOFR		0.10%
Extension option period		12 months
Extension fee percentage		0.125%
Number of extensions \| extension	2	2
Credit Agreement \| Term Loan Facility \| Term Loan Facility \| Minimum
Debt
Variable rate, spread over SOFR		0.85%
Credit Agreement \| Term Loan Facility \| Term Loan Facility \| Maximum
Debt
Variable rate, spread over SOFR		1.70%
2.25%, $400,000 aggregate principal \| Unsecured Senior Notes
Debt
Interest rate	2.25%	2.25%
Debt instrument, face amount	$ 400,000,000	$ 400,000,000
Carrying Value	399,532,000	399,532,000	398,699,000
Unamortized discounts and/or commissions included in carrying value	$ 382,000	$ 382,000	1,100,000
Effective interest rate on debt	2.48%	2.48%
5.25%, $345,000 aggregate principal \| Unsecured Senior Notes
Debt
Interest rate	5.25%	5.25%
Debt instrument, face amount	$ 345,000,000	$ 345,000,000
Carrying Value	338,990,000	338,990,000	337,588,000
Unamortized discounts and/or commissions included in carrying value	$ 5,300,000	$ 5,300,000	6,600,000
Effective interest rate on debt	5.83%	5.83%
Exchange rate of notes	0.0334962
Exchange price (in dollars per share) \| $ / shares	$ 29.85	$ 29.85
2.00%, $400,000 aggregate principal \| Unsecured Senior Notes
Debt
Interest rate	2.00%	2.00%
Debt instrument, face amount	$ 400,000,000	$ 400,000,000
Carrying Value	398,334,000	398,334,000	397,961,000
Unamortized discounts and/or commissions included in carrying value	$ 1,200,000	$ 1,200,000	1,500,000
Effective interest rate on debt	2.09%	2.09%
2.75%, $600,000 aggregate principal \| Unsecured Senior Notes
Debt
Interest rate	2.75%	2.75%
Debt instrument, face amount	$ 600,000,000	$ 600,000,000
Carrying Value	593,186,000	593,186,000	592,330,000
Unamortized discounts and/or commissions included in carrying value	$ 5,900,000	$ 5,900,000	6,700,000
Effective interest rate on debt	2.94%	2.94%
2.90%, $400,000 aggregate principal \| Unsecured Senior Notes
Debt
Interest rate	2.90%	2.90%
Debt instrument, face amount	$ 400,000,000	$ 400,000,000
Carrying Value	396,020,000	396,020,000	395,692,000
Unamortized discounts and/or commissions included in carrying value	$ 3,300,000	$ 3,300,000	3,500,000
Effective interest rate on debt	3.01%	3.01%
Unsecured note payable \| Unsecured note payable
Debt
Interest rate	0.00%	0.00%
Carrying Value	$ 109,000	$ 109,000	251,000
Unamortized discounts and/or commissions included in carrying value	$ 2,000	$ 2,000	$ 10,000