Leasing Activities (Schedule of Lease Receivables) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Lease Receivables [Line Items]
Operating Leases, Future Minimum Payments Receivable, Current	$ 617,690
Operating Leases, Future Minimum Payments Receivable, in Two Years	602,815
Operating Leases, Future Minimum Payments Receivable, in Three Years	549,298
Operating Leases, Future Minimum Payments Receivable, in Four Years	487,831
Operating Leases, Future Minimum Payments Receivable, in Five Years	421,855
Operating Leases, Future Minimum Payments Receivable, Thereafter	1,898,411
Operating Leases, Future Minimum Payments Receivable	4,577,900
Tenant Reimbursements	$ 193,700	$ 193,400	$ 201,800