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Subsequent Events (Details) (USD $)
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3 Months Ended | 0 Months Ended | 1 Months Ended | 3 Months Ended | 0 Months Ended | 3 Months Ended | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Mar. 31, 2012
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Mar. 31, 2011
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Dec. 31, 2011
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May 03, 2012
12310 Sunrise Valley Drive [Member]
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Apr. 30, 2012
510 Madison Avenue [Member]
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May 01, 2012
Bedford Business Park [Member]
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May 08, 2012
Atm Program [Member]
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May 08, 2012
Atm Program [Member]
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Mar. 31, 2012
Atm Program [Member]
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Apr. 02, 2012
One Freedom Square [Member]
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Mar. 31, 2012
One Freedom Square [Member]
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May 01, 2012
Office/Technical Properties [ Member]
Bedford Business Park [Member]
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May 01, 2012
Class A Office Properties [ Member]
Bedford Business Park [Member]
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| Subsequent Event [Line Items] | |||||||||||||
| Shares issued | 149,463,241 | 148,186,511 | 643,600 | 643,600 | 1,048,800 | ||||||||
| At the market stock offering program, gross proceeds | $ 68,400,000 | $ 110,500,000 | |||||||||||
| At the market stock offering program, net proceeds | 109,330,000 | 345,369,000 | 67,700,000 | 109,300,000 | |||||||||
| At the market stock offering program remaining amount available for issuance | 376,200,000 | 444,600,000 | |||||||||||
| Repayments of mortgage notes payable | 150,519,000 | 8,777,000 | 65,100,000 | ||||||||||
| Interest at a fixed rate | 7.75% | ||||||||||||
| Maturity date | Jun. 30, 2012 | ||||||||||||
| Penalty for early repayment of debt | 0 | ||||||||||||
| Percentage of office component of the development project placed in-service | 100.00% | 100.00% | |||||||||||
| Disposition price | $ 62,800,000 | ||||||||||||
| Number of real estate properties | 2 | 1 | |||||||||||
| Square footage of real estate property | 268,000 | 347,000 | 470,000 | ||||||||||