Operating Leases (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Percentage of annualized lease revenue	87.00%
Operating Leases, Future Minimum Payments Receivable [Abstract]
2017	$ 434,871
2018	426,532
2019	395,212
2020	359,636
2021	323,940
Thereafter	1,615,265
Total	$ 3,555,456
Customer Concentration Risk [Member] | Federal Governmental Agencies [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Concentration risk, percentage	8.20%