Summary of Significant Accounting Policies Summary of Significant Accounting Policies - Development Costs (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Development Costs [Line Items]
Development expenses	$ 16,000,000	$ 12,207,000	$ 18,009,000	$ 0
Project development costs incurred		12,200,000	18,000,000
Architectural Fees [Member]
Development Costs [Line Items]
Project development costs incurred		2,100,000	10,400,000
Legal, Construction Manager Costs, Consultants, And Other Professional Services [Member]
Development Costs [Line Items]
Project development costs incurred		5,100,000
Shared Development Expenses [Member]
Development Costs [Line Items]
Project development costs incurred			1,900,000
Legal Expense [Member]
Development Costs [Line Items]
Project development costs incurred		3,100,000	2,300,000
Construction Manager Costs [Member]
Development Costs [Line Items]
Project development costs incurred			1,000,000
Professional Services [Member]
Development Costs [Line Items]
Project development costs incurred		1,000,000	900,000
Agreement Payments [Member]
Development Costs [Line Items]
Project development costs incurred		$ 900,000	$ 1,500,000