Summary of Significant Accounting Policies - Compensation Costs (Including Bonuses and Benefits) Capitalized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	$ 6,717	$ 7,291	$ 5,194
Development [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	3,182	2,641	1,749
Redevelopment [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	144	221	184
Tenant Improvements [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	$ 3,391	$ 4,429	$ 3,261