Real Estate (Summary of Real Estate Subject to Operating Leases) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property Subject to or Available for Operating Lease [Line Items]
Real estate subject to operating leases, gross	$ 6,596,728	$ 5,787,845
Less accumulated depreciation and amortization	(739,505)	(617,786)
Real estate subject to operating leases before work in process	5,857,223	5,170,059
Work in progress	24,057	61,354	$ 28,908
Accounted for using the operating method, net of accumulated depreciation and amortization	5,881,280	5,231,413
Revenue recognized	(12)	153	$ 1,521
Balance of accrued rental income	25,101	25,529
Allowances	3,078
Land and improvements
Property Subject to or Available for Operating Lease [Line Items]
Land and improvements	2,102,915	1,909,569
Buildings and improvements
Property Subject to or Available for Operating Lease [Line Items]
Buildings and improvements	4,489,248	3,876,986
Leasehold interests
Property Subject to or Available for Operating Lease [Line Items]
Leasehold interests	4,565	1,290
Work in progress
Property Subject to or Available for Operating Lease [Line Items]
Work in progress	$ 24,057	$ 61,354