Summary of Significant Accounting Policies - Compensation Costs (Including Bonuses and Benefits) Capitalized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	$ 7,291	$ 5,194	$ 3,673
Development [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	2,641	1,749	156
Redevelopment [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	221	184	194
Tenant Improvements [Member]
Construction in Progress [Line Items]
Salaries including bonuses and benefits, capitalized during the period	$ 4,429	$ 3,261	$ 3,323