Basis of Presentation (Narrative) (Details) - Accounting Standards Update 2016-02 - Rental revenues - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Basis of Presentation [Line Items]
Property rentals	$ 437,560	$ 1,322,265
Tenant expense reimbursement	$ 66,387	$ 185,009