Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Capitalized interest	$ 4.6	$ 5.4
Capitalized real estate taxes	1.6	$ 0.9
Outstanding notes receivable	$ 17.0		$ 13.2
Weighted average interest rate on outstanding notes receivable	4.10%	4.30%
Remaining commitment under notes receivable	$ 4.6
General Partner of Consolidated Operating Partnerships, Ownership Interest	1.00%
Interest Expense [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from deferred financing charges		$ 0.4
Depreciation and Amortization [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from deferred financing charges		$ 0.4
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Outstanding common limited partnership units, ownership interest	92.00%
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Outstanding common limited partnership units, ownership interest	94.00%