Organization (Details 2)	Dec. 31, 2012 State property sqft	Dec. 31, 2012 Discontinued operations property	Apr. 24, 2009 CWH property
Organization
Number of properties owned	84	2	29
Number of states in which owned properties located	32
Rentable area of properties (in square feet)	10,200,000

The number of states in which real estate owned by the entity is located as of the balance sheet date.

No definition available.

Name:	gov_NumberOfStatesInWhichRealEstatePropertiesHeld
Namespace Prefix:	gov_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant