Real Estate (Real Estate Subject to Operating Leases) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Property Subject to or Available for Operating Lease [Line Items]
Land and improvements	$ 2,463,934	$ 2,368,891
Buildings and improvements	5,752,916	5,461,888
Leasehold interests	355	3,630
Real estate subject to operating leases, gross	8,217,205	7,834,409
Less accumulated depreciation and amortization	(1,109,285)	(1,003,519)
Real estate subject to operating leases, net, before work in process	7,107,920	6,830,890
Work in progress for buildings and improvements	13,236	8,017
Accounted for using the operating method, net of accumulated depreciation and amortization	7,121,156	6,838,907
Asset under construction
Property Subject to or Available for Operating Lease [Line Items]
Land and improvements	$ 11,707	$ 5,571