Real Estate (Summary of Real Estate Subject to Operating Leases) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Land and improvements	$ 2,489,243	$ 2,490,935
Buildings and improvements	6,009,797	5,916,149
Leasehold interests	355	355
Real estate subject to operating leases, gross	8,499,395	8,407,439
Less accumulated depreciation and amortization	(1,317,407)	(1,147,795)
Real estate subject to operating leases, net, before work in process	7,181,988	7,259,644
Work in progress – improvements	26,673	27,438	$ 8,017
Accounted for using the operating method, net of accumulated depreciation and amortization	7,208,661	7,287,082
Asset under construction
Property, Plant and Equipment [Line Items]
Land and improvements	$ 8,421	$ 16,930