Property Dispositions (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) property	Sep. 30, 2018 USD ($) property	Sep. 30, 2019 USD ($) property	Sep. 30, 2018 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sale of real estate investments	$ 14,546	$ 108,634	$ 98,006	$ 151,142
Gain on sale of real estate, net of tax	887	3,228	17,819	4,448
Provision for impairment, net of tax	$ (14)	$ 855	$ 12,099	$ 29,443
Number of properties held for sale | property	2		2
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%
Real Estate Sold [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Provision for impairment, net of tax	$ 194	$ 855	$ 1,860	$ 29,443
Operating Properties [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties sold | property	1	3	5	7
Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties sold | property	2	3	5	6