Acquisitions, Dispositions, Discontinued Operations and Assets Held for Sale Acquisitions, Dispositions, Discontinued Operations and Assets Held for Sale (Income from Discontinued Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property revenues		$ 14,592	$ 19,184	$ 42,637
Property expenses		(5,442)	(6,898)	(15,364)
Property revenues less property expenses		9,150	12,286	27,273
Property management expense		(184)	(242)	(505)
Depreciation and amortization		(4,059)	(4,327)	(11,936)
Income tax expense		0	(112)	0
Income from discontinued operations	$ 0	$ 4,907	$ 7,605	$ 14,832