Property Dispositions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) property	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 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	$ 137,572	$ 250,445	$ 110,015
Gain on sale of real estate, net of tax	24,242	28,343	27,432
Provision for impairment, net of tax	$ 54,174	38,437	$ 0
Number of properties held for sale | property	1
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	$ 1,836	$ 31,041
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	7	10	6
Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties sold | property	6	9	9