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

Annual report pursuant to Section 13 and 15(d)

Debt (Details)

Debt (Details) (USD $)	12 Months Ended					12 Months Ended				1 Months Ended	12 Months Ended		12 Months Ended			4 Months Ended	12 Months Ended		4 Months Ended			1 Months Ended	4 Months Ended			4 Months Ended	1 Months Ended			1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended
Debt (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011 Mortgage and Other Secured Loans:	Dec. 31, 2010 Mortgage and Other Secured Loans:	Dec. 31, 2011 Fixed rate mortgage loans	Dec. 31, 2010 Fixed rate mortgage loans	Dec. 31, 2011 Revolving Construction Facility	Dec. 31, 2010 Revolving Construction Facility	Sep. 30, 2011 Variable rate secured loans loan	Dec. 31, 2011 Variable rate secured loans	Dec. 31, 2010 Variable rate secured loans	Dec. 31, 2011 Other construction loan facilities	Dec. 31, 2010 Other construction loan facilities	Dec. 31, 2011 Other construction loan facilities LIBOR 30-day	Dec. 31, 2011 Revolving Credit Facility Y	Dec. 31, 2010 Revolving Credit Facility	Sep. 01, 2011 Revolving Credit Facility	Dec. 31, 2011 Revolving Credit Facility Maximum	Dec. 31, 2011 Revolving Credit Facility Minimum	Dec. 31, 2011 Revolving Credit Facility LIBOR 30-day	Sep. 30, 2011 Term Loan Facility	Dec. 31, 2011 Term Loan Facility Y	Dec. 31, 2011 Term Loan Facility Maximum	Dec. 31, 2011 Term Loan Facility Minimum	Dec. 31, 2011 Term Loan Facility LIBOR 30-day	Sep. 30, 2011 Revolving facilities and variable rate secured loans	Dec. 31, 2011 Unsecured notes payable	Dec. 31, 2010 Unsecured notes payable	Apr. 30, 2010 4.25% Exchangeable Senior Notes	Dec. 31, 2011 4.25% Exchangeable Senior Notes	Dec. 31, 2010 4.25% Exchangeable Senior Notes	Apr. 07, 2010 4.25% Exchangeable Senior Notes	Sep. 30, 2011 3.5% Exchangeable Senior Notes	Dec. 31, 2011 3.5% Exchangeable Senior Notes	Dec. 31, 2010 3.5% Exchangeable Senior Notes	Dec. 31, 2009 3.5% Exchangeable Senior Notes	Sep. 15, 2011 3.5% Exchangeable Senior Notes
Debt
Maximum Availability													$ 123,802,000			$ 1,000,000,000		$ 1,000,000,000					$ 400,000,000
Carrying Value	2,426,303,000	2,323,681,000		1,131,970,000	1,643,005,000	1,052,421,000	1,173,358,000		142,339,000		39,213,000	310,555,000	40,336,000	16,753,000		662,000,000	295,000,000						400,000,000					5,050,000	1,947,000		227,283,000	223,846,000				159,883,000
Stated interest rate (as a percent)																												0.00%			4.25%		4.25%			3.50%		3.50%
Stated Interest Rates, low end of range (as a percent)						5.20%
Stated Interest Rates, high end of range (as a percent)						7.87%
Description of variable rate basis											LIBOR		LIBOR			LIBOR					LIBOR		LIBOR			LIBOR
Variable rate, spread (as a percent)											2.25%		2.75%						2.50%	1.75%				2.40%	1.65%
Variable rate, spread low end of range (as a percent)															1.95%						1.75%					1.65%
Variable rate, spread high end of range (as a percent)															2.75%						2.50%					2.40%
Unamortized discount included in carrying value																												1,800,000	1,100,000		12,700,000	16,200,000				2,600,000
Unamortized premium included in carrying value						2,400,000	3,200,000
Extension option period (in years)																1							1
Interest rate on debt (as a percent)											2.52%												2.18%
Expansion right, maximum borrowing capacity																1,500,000,000
Amount available as a percentage of unencumbered Asset value																60.00%
Extension fee as a percentage of total availability of the facility																0.20%							0.20%
Percentage of quarterly fee																			0.35%	0.25%
Remaining borrowing capacity																329,600,000
Number of loans repaid upon entry into Revolving Credit Facility and Term Loan Agreement										2
Initial amount borrowed																						400,000,000								240,000,000
Additional borrowing capacity available provided there is no default under the agreement																							100,000,000
Amount of loans repaid upon entry into Revolving Credit Facility and Term Loan Agreement										270,300,000
Loss on early extinguishment of debt	1,683,000																										1,700,000
Amount of loans repaid upon entry into Revolving Credit Facility and Term Loan Agreement																																		162,500,000
Principal amount of debt	2,438,471,000																																221,400,000			162,500,000
Exchange rate per $1000 principal amount (in common shares)																															20.8513
Convertible debt principal amount, basis for exchange																															1,000
Exchange price per common share based on exchange rate (in dollars per share)																															$ 47.96
Percentage over the entity's common stock price at the time of issuance which was used to determine the initial exchange rate																														20.00%
Percentage over the entity's common stock price at the time of issuance which was used to determine the initial exchange rate																															100.00%
Initial equity component of debt																																	18,600,000
Finance fees recognized in relation to notes in equity	44,159,000	31,784,000
Repurchase of notes, percentage of principal paid																																						100.00%
Effective interest rate, including amortization of issuance costs (as a percent)																															6.05%							5.97%
Interest expense at stated interest rate																															10,200,000	7,480,000			4,013,000	5,687,000	5,687,000
Interest expense associated with amortization of discount	5,540,000	5,841,000	3,412,000																												3,437,000	2,445,000			2,617,000	3,736,000	3,520,000
Nonrecourse mortgage loan secured by a property in default				15,200,000
Estimated fair value of property secured by nonrecourse mortgage loan in default				9,000,000
Total interest expenses																															13,637,000	9,925,000			6,630,000	9,423,000	9,207,000
Weighted average borrowings																$ 482,300,000	$ 337,200,000
Weighted average interest rate (as a percent)																1.65%	1.11%
Weighted average interest rate (as a percent)						6.01%		2.82%								1.68%