COPT Defense Properties Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Debt, Net - Narrative (Details)

Debt, Net - Narrative (Details)					12 Months Ended
Debt, Net - Narrative (Details)	Sep. 12, 2023 USD ($)	Nov. 17, 2021 USD ($)	Aug. 11, 2021 USD ($)	Mar. 11, 2021 USD ($)	Dec. 31, 2023 USD ($) day extension $ / shares	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Oct. 26, 2022 USD ($)	Nov. 18, 2021 USD ($)	Apr. 12, 2021 USD ($)
Debt Instrument [Line Items]
Loss on early extinguishment of debt					$ 0	$ (609,000)	$ (100,626,000)
Revolving Credit Facility \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, additional spread					0.0010
Weighted average interest rate					6.49%
Term Loan Facility
Debt Instrument [Line Items]
Number of extensions \| extension					2
Extension option period					12 months
Line of credit facility, extension fee					0.125%
Loan amount								$ 400,000,000
Loan increase								$ 150,000,000
Repayments of term loan						300,000,000	100,000,000
Term Loan Facility \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, additional spread					0.0010
Interest rate					6.74%
Minimum \| Revolving Credit Facility \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, spread					0.725%
Minimum \| Term Loan Facility \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, spread					0.85%
Maximum \| Revolving Credit Facility \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, spread					1.40%
Maximum \| Term Loan Facility \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, spread					1.70%
Revolving Credit Facility
Debt Instrument [Line Items]
Weighted average borrowings					$ 133,300,000	$ 202,800,000
Weighted average interest rate					6.17%	3.31%
Revolving Credit Facility \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, additional spread					0.0010
Revolving Credit Facility \| Minimum \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, spread					0.725%
Revolving Credit Facility \| Maximum \| Secured Overnight Financing Rate
Debt Instrument [Line Items]
Variable rate, spread					1.40%
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Current borrowing capacity					$ 600,000,000				$ 600,000,000
Number of extensions \| extension					2
Extension option period					6 months
Line of credit facility, extension fee					0.0625%
Remaining borrowing capacity					$ 525,000,000
Line of Credit \| Revolving Credit Facility \| Minimum
Debt Instrument [Line Items]
Commitment fee percentage					0.125%
Line of Credit \| Revolving Credit Facility \| Maximum
Debt Instrument [Line Items]
Commitment fee percentage					0.30%
Unsecured Debt \| Term Loan Facility
Debt Instrument [Line Items]
Loan amount									$ 125,000,000
Unsecured Senior Notes \| 2.25%, 2.75%, 2.00% and 2.90% Senior Notes
Debt Instrument [Line Items]
Redemption price					100.00%
Unsecured Senior Notes \| 2.25% Senior Notes
Debt Instrument [Line Items]
Loan amount					$ 400,000,000
Interest rate					2.25%
Basis point used in determining redemption price prior to maturity					0.35%
Unsecured Senior Notes \| 2.75%, $600,000 aggregate principal
Debt Instrument [Line Items]
Loan amount				$ 600,000,000	$ 600,000,000
Interest rate				2.75%	2.75%
Initial offering price				98.95%
Proceeds from issuance of debt				$ 589,800,000
Unsecured Senior Notes \| 2.75%, $600,000 aggregate principal \| Adjusted Treasury
Debt Instrument [Line Items]
Basis point used in determining redemption price prior to maturity					0.25%
Unsecured Senior Notes \| 2.00%, $400,000 aggregate principal
Debt Instrument [Line Items]
Loan amount			$ 400,000,000		$ 400,000,000
Interest rate			2.00%		2.00%
Initial offering price			99.97%
Proceeds from issuance of debt			$ 397,400,000
Unsecured Senior Notes \| 2.00%, $400,000 aggregate principal \| Adjusted Treasury
Debt Instrument [Line Items]
Basis point used in determining redemption price prior to maturity					0.20%
Unsecured Senior Notes \| 2.90%, $400,000 aggregate principal
Debt Instrument [Line Items]
Loan amount		$ 400,000,000			$ 400,000,000
Interest rate		2.90%			2.90%
Initial offering price		99.53%
Proceeds from issuance of debt		$ 395,400,000
Unsecured Senior Notes \| 2.90%, $400,000 aggregate principal \| Adjusted Treasury
Debt Instrument [Line Items]
Basis point used in determining redemption price prior to maturity					0.25%
Unsecured Senior Notes \| 5.25%, $345,000 aggregate principal
Debt Instrument [Line Items]
Loan amount	$ 345,000,000				$ 345,000,000
Interest rate	5.25%				5.25%
Proceeds from issuance of debt	$ 336,400,000
Redemption price					100.00%
Initial exchange rate per $1000 principal amount of the notes (in shares)	0.0333739
Exchange price per share (in dollars per share) \| $ / shares					$ 29.96
Threshold percentage of stock price trigger					130.00%
Threshold trading days \| day					20
Threshold consecutive trading days \| day					30
Unsecured Senior Notes \| 3.60% Senior Notes due 2023 and 5.25% Senior Notes due 2024
Debt Instrument [Line Items]
Loss on early extinguishment of debt							(58,400,000)
Unsecured Senior Notes \| 3.60% Senior Notes due 2023
Debt Instrument [Line Items]
Repurchased face amount				184,400,000							$ 165,600,000
Repurchase face amount plus prepayment premium				196,700,000							176,300,000
Unsecured Senior Notes \| 5.25% Senior Notes due 2024
Debt Instrument [Line Items]
Repurchased face amount				145,600,000							104,400,000
Repurchase face amount plus prepayment premium				$ 164,700,000							$ 117,700,000
Unsecured Senior Notes \| 5.00% Senior Notes due 2025
Debt Instrument [Line Items]
Repurchased face amount										$ 300,000,000
Repurchase face amount plus prepayment premium										$ 336,400,000
Loss on early extinguishment of debt							$ (38,200,000)