Property Dispositions (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) property	Jun. 30, 2018 USD ($) property	Jun. 30, 2019 USD ($) property	Jun. 30, 2018 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sale of real estate investments	$ 927	$ 38,781	$ 83,460	$ 42,008
Gain on sale of real estate, net of tax	442	1,123	16,932	1,219
Provision for impairment, net of tax	$ 10,441	$ 12,533	$ 12,113	$ 28,587
Number of properties held for sale | property	1		1
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	$ (6)	$ 2,974	$ 1,666	$ 3,348
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		3	4	4
Land [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	3	3