Basis of Presentation and Significant Accounting Policies (Basis of Presentation) (Details) - Accounting Standards Update 2016-02 - Rental revenues - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Basis of Presentation [Line Items]
Property rentals	$ 1,760,205	$ 1,714,952
Tenant expense reimbursement	$ 247,128	$ 233,424