Summary of Significant Accounting Policies - Revenues - Accounts Receivables (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) joint_venture	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Tenant Receivables	$ 15,599	$ 14,521
Document Fiscal Year Focus	2016
Current Fiscal Year End Date	--12-31
Number of Joint Ventures, Unilateral Dissolution Right | joint_venture	5
Provision for doubtful accounts	$ 1,705	2,364	$ 2,192
Provision for Loan and Lease Losses	2,271	714	$ 107
Accrued CAM, insurance and tax reimbursements receivables	9,221	12,358
Other receivables	12,058	10,708
Straight Line Rent Receivable, Gross	73,384	64,757
COMBINED ABOVE-Notes receivable (note 5)	10,481	10,480
Less: allowance for doubtful accounts	(5,460)	(5,295)
Straight line rent receivable reserve	(3,561)	(1,365)
Accounts Receivable, Net	$ 111,722	$ 106,164
Percentage Of Revenue By Customer	5.00%
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage Of Revenue By Customer	5.00%