Property Dispositions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from Sale of Real Estate	$ 2,747	$ 82,364	$ 7,219	$ 82,364
Gain (Loss) on Sale of Properties	1,691	13,127	2,406	13,127
Wholly Owned Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percent interest sold	100.00%	100.00%	100.00%	100.00%
Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues		5,119		10,850
Operating expenses		2,419		5,527
Operating income from discontinued operations		2,700
Parent Company [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain (Loss) on Sale of Properties	1,691	1,717	2,406	1,717
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0	11,410	0	11,410
Revenues	134,892	122,307	268,173	242,685
Operating expenses	87,437	78,858	177,018	159,841
Operating income from discontinued operations	$ 0	$ 2,700	$ 0	$ 5,323
Operating Segments [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	1	4	2	4
Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of operating properties sold	1	0	3	0