Annual report pursuant to Section 13 and 15(d)

Mortgage Notes Payable (Details)

v2.4.0.6
Mortgage Notes Payable (Details) (USD $)
 12 Months Ended
Dec. 31, 2011
building
Dec. 31, 2010
Mortgage Loans on Real Estate [Line Items]    
Minimum, Buildings or Land, Collateral for Mortgage Notes Payable 1  
Debt Instrument, Interest Rate, Effective Percentage Rate Range, Minimum 5.00%  
Carrying Amount, Mortgaged Properties $ 678,900,000 $ 570,500,000
Mortgage notes payable 427,710,000 361,860,000
Mortgage note interest rate, percentage 3.875%  
Shady Grove Medical Village II [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Repayment of secured mortgage notes 9,100,000  
Columbia Park Road And Dulles Business Park [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Repayment of secured mortgage notes 17,500,000  
Increase in sales price for partially offsetting the penalties incurred due to prepayment of mortgage notes 875,000  
Prepayment penalties incurred on mortgage notes 1,000,000  
Prosperity Medical Center 5.36% [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 31,169,000 31,886,000
Mortgage note, fair value interest rate 5.36% [1]  
Prosperity Medical Center 5.34% [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 11,828,000 12,101,000
Mortgage note, fair value interest rate 5.34% [1]  
Shady Grove Medical Village Ii Member
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 0 9,375,000
Mortgage note, fair value interest rate 6.98% [1]  
Frederick Crossing [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 21,700,000 22,268,000
Mortgage note, fair value interest rate 5.95% [1]  
9707 Medical Center [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 4,780,000 [2] 4,955,000 [2]
Mortgage note, fair value interest rate 5.32% [1],[2]  
Plumtree [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 4,419,000 4,512,000
Mortgage note, fair value interest rate 5.68% [1]  
15005 Shady Grove [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 7,974,000 8,149,000
Mortgage note, fair value interest rate 5.73% [1]  
West Gude [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 30,761,000 31,486,000
Mortgage note, fair value interest rate 5.86% [1]  
Woodholme Medical Center [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 19,954,000 20,285,000
Mortgage note, fair value interest rate 5.29% [1]  
Ashburn Farm Office 5.56% [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 2,438,000 2,556,000
Mortgage note, fair value interest rate 5.56% [1]  
Ashburn Farm Office 5.69% [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 2,159,000 2,285,000
Mortgage note, fair value interest rate 5.69% [1]  
3801 Connecticut [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 35,399,000 81,029,000 [3]
Mortgage note, fair value interest rate 5.71% [1],[3]  
3801 Connecticut, Walker House, Bethesda Hill [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 81,029,000 [3]  
2445 M Street [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 95,593,000 [4] 94,339,000 [4]
Mortgage note, fair value interest rate 5.62% [1],[4]  
Kenmore Apartments [Member]
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 36,097,000 36,634,000
Mortgage note, fair value interest rate 5.37% [1]  
Olney Village Center Member
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable 23,873,000 0
Mortgage note, fair value interest rate 4.94% [1]  
John Marshall II Member
    
Mortgage Loans on Real Estate [Line Items]    
Mortgage notes payable $ 53,936,000 $ 0
Mortgage note, fair value interest rate 5.79% [1]  
[1] Yield on the assumption/issuance date, including the effects of any premiums, discounts or fair value adjustments on the notes.
[2] The mortgage bears a set interest rate through June 30, 2012, at which time the rate will be reset based on the Moody's Long-term Corporate Bond Yield Average, but never lower than 5.0% per annum. The interest rate will be reset annually thereafter for the duration of the note. Principal and interest are payable monthly until July 1, 2028, at which time all unpaid principal and interest are payable in full. During the first 90 days of 2013, the lender has the option to elect to accelerate the maturity date of the note to July 1, 2013. For the remainder of 2013, we have the right to prepay the note without any prepayment penalties.
[3] Interest only is payable monthly until the maturity date, which can be extended for one year upon which the interest rate is reset on June 1, 2016. At maturity on June 1, 2017, all unpaid principal and interest are payable in full.
[4] Interest only is payable monthly until the maturity date upon which all unpaid principal and interest are payable in full.