Organization and Ownership (Details Textuals)	12 Months Ended
	Dec. 31, 2012 building	Dec. 31, 2011
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Stabilized occupancy	95.00%
Number of properties of the company in Washington	10
Percentage of general partnership interest owned by the company in the Operating Partnership	97.60%	97.20%
Percentage of Common limited partnership interest owned by certain non-affiliated investors and certain directors and officers of the Company in the Operating Partnership	2.40%	2.80%
Percentage of General partnership interest owned by wholly-owned subsidiary of the Company	1.00%
Percentage of limited partnership interest owned by Operating Partnership	99.00%