Real Estate (Dispositions) (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($) property	Sep. 30, 2015 USD ($) property	Sep. 30, 2016 USD ($) property	Sep. 30, 2015 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense	$ 0	$ (545)	$ 0	$ (491)
Assets Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of sold properties - gain on disposition of real estate | property	7	5	24	14
Gain on disposition of real estate	$ 4,505	$ 1,970	$ 22,558	$ 9,231
Income tax expense	0	(56)	0	(86)
Gain on disposition of real estate, net of income tax expense	$ 4,505	$ 1,914	$ 22,558	$ 9,145