Investments in Unconsolidated Real Estate Joint Ventures (Summary Balance Sheets for Unconsolidated Joint Ventures) (Details) (Partnership Interest [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Partnership Interest [Member]
Assets
Land	$ 91,922	$ 102,601
Buildings, improvements and fixtures	496,201	542,501
Construction in progress, including land	128,529	104,780
Rental property, at cost, total	716,652	749,882
Accumulated depreciation	(38,236)	(48,233)
Total rental property, net	678,416	701,649
Cash and cash equivalents	56,119	46,917
Deferred lease costs, net	19,345	21,234
Deferred debt origination costs, net	5,256	5,995
Prepaids and other assets	14,648	12,766
Total assets	773,784	788,561
Liabilities and Owners' Equity
Mortgages payable	370,244	358,219
Accounts payable and other liabilities	46,971	70,795
Total liabilities	417,215	429,014
Owners' equity	356,569	359,547
Total liabilities and owners' equity	$ 773,784	$ 788,561