Capital and Financing Transactions - Mortgage Notes Payable (Details) - USD ($) $ in Thousands			3 Months Ended		6 Months Ended
	Apr. 11, 2016	Apr. 06, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Debt Instrument [Line Items]
Gain on extinguishment of debt			$ 462	$ (4,919)	$ 462	$ (4,840)
Construction loan payable balance			39,800		39,800
Hayden Ferry Lakeside III | Fund II
Debt Instrument [Line Items]
Proceeds from construction loans					8,100
Mortgages
Debt Instrument [Line Items]
Mortgage notes payable			1,100,000		1,100,000
Unamortized net premiums on debt			13,500		13,500
Unamortized debt issuance expense			$ 2,400		$ 2,400
Weighted average interest rate (as a percent)			4.10%		4.10%
Mortgages | City West Place [Member]
Debt Instrument [Line Items]
Amount of debt paid in full		$ 114,000
Gain on extinguishment of debt					$ 154
Mortgages | Lincoln Place
Debt Instrument [Line Items]
Amount of debt paid in full	$ 47,900
Gain on extinguishment of debt					$ 308