|
Concentration of Rental Revenue (Details)
|
12 Months Ended | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Dec. 31, 2011
region
|
Dec. 31, 2011
Rental revenue
Tenants
tenant
|
Dec. 31, 2011
Rental revenue
Tenants
United States Government
|
Dec. 31, 2010
Rental revenue
Tenants
United States Government
|
Dec. 31, 2009
Rental revenue
Tenants
United States Government
|
Dec. 31, 2011
Rental revenue
Tenants
Northrop Grumman Corporation
|
Dec. 31, 2010
Rental revenue
Tenants
Northrop Grumman Corporation
|
Dec. 31, 2009
Rental revenue
Tenants
Northrop Grumman Corporation
|
Dec. 31, 2011
Rental revenue
Tenants
Booz Allen Hamilton, Inc.
|
Dec. 31, 2010
Rental revenue
Tenants
Booz Allen Hamilton, Inc.
|
Dec. 31, 2009
Rental revenue
Tenants
Booz Allen Hamilton, Inc.
|
Dec. 31, 2011
Rental revenue
Tenants
Five largest tenants
|
Dec. 31, 2010
Rental revenue
Tenants
Five largest tenants
|
Dec. 31, 2009
Rental revenue
Tenants
Five largest tenants
|
Dec. 31, 2011
Construction contract revenue
United States Government
|
Dec. 31, 2010
Construction contract revenue
United States Government
|
Dec. 31, 2009
Construction contract revenue
United States Government
|
|
| Concentration Risk | |||||||||||||||||
| Percentage required for qualification as major customer | 5.00% | ||||||||||||||||
| Percentage of revenue | 17.00% | 16.00% | 15.00% | 8.00% | 9.00% | 8.00% | 6.00% | 5.00% | 6.00% | 38.00% | 35.00% | 34.00% | 90.00% | 90.00% | 90.00% | ||
| Number of tenants from which the entity has recognized the most rental revenue aggregated for revenue concentration disclosure | 5 | ||||||||||||||||
| Number of regions with real estate operations which are not located in the Mid-Atlantic region of the United States | 2 | ||||||||||||||||