Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Operating Leases
Number of properties | item	4,944
Number of U.S. states where properties are owned | item	49
Single-tenant properties | item	4,920
Single-tenant properties (as a percent)	99.50%
Vacant properties available for lease or sale | item	84
Percentage rents	$ 5,300	$ 4,500	$ 3,600
Minimum future annual rents to be received on the operating leases
2017	1,146,053
2018	1,092,071
2019	1,042,068
2020	992,192
2021	940,379
Thereafter	6,043,472
Total	$ 11,256,235