Real Estate (Summary of Real Estate Subject to Operating Leases) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Land and improvements	$ 2,492,984	$ 2,369,014
Buildings and improvements	5,917,525	5,470,968
Leasehold interests	355	3,630
Real estate subject to operating leases, gross	8,410,864	7,843,612
Less accumulated depreciation and amortization	(1,148,277)	(1,006,183)
Real estate subject to operating leases, net, before work in process	7,262,587	6,837,429
Work in progress - improvements	27,438	8,017	$ 41,920
Accounted for using the operating method, net of accumulated depreciation and amortization	7,290,025	6,845,446
Asset under construction
Property, Plant and Equipment [Line Items]
Land and improvements	$ 16,930	$ 5,571