Property Transactions (Components of Income (Loss) from Discontinued Operations) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Document Fiscal Year Focus	2014	2013	2012
Components of Income (Loss) from Discontinued Operations
Income from discontinued operations	$ 1,800	$ 3,299	$ 1,907
Discontinued Operations [Member]
Components of Income (Loss) from Discontinued Operations
Rental property revenues	2,927	10,552	33,918
Other revenues	29	40	3,557
Third party management and leasing revenues	0	76	16,364
Third party management and leasing expenses	0	(99)	(13,678)
Impairment losses	0	0	(13,791)
Depreciation and amortization	0	(3,083)	(13,479)
Rental property operating expenses	(28)	(25)	(49)
Rental property operating expenses	(1,128)	(4,162)	(10,935)
Income from discontinued operations	$ 1,800	$ 3,299	$ 1,907