Investments in real estate, net Dispositions (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 property	Sep. 30, 2013
Dispositions [Line Items]
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes	$ 8,000	$ 0	$ 805,000	$ 772,000
Number of Land Parcels Sold			4
Proceeds from Sale of Real Estate			29,400,000
Non-Cluster market [Member]
Dispositions [Line Items]
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes			0
Number of Land Parcels Sold			3
Seattle Market [Member]
Dispositions [Line Items]
Gain (Loss) on Sale of Properties, Net of Applicable Income Taxes			$ 800,000
Number of Land Parcels Sold			1