Properties (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Land	$ 232,744	$ 233,301
Buildings, improvements, and equipment	4,395,463	4,342,664
Construction in process and pre-development costs	102,854	141,604
Real Estate Investment Property, at Cost	4,731,061	4,717,569
Accumulated depreciation and amortization	(1,514,992)	(1,404,692)
Real Estate Investment Property, Net	3,216,069	3,312,877
Real Estate Accumulated Depreciation, Depreciation Expense	172,960	155,133	$ 161,091
Pre-development activities expense	$ 1,900	$ 3,800	$ 5,600