Disposal of Operating Properties - Additional Information (Details) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2015 USD ($) property	Sep. 30, 2016 USD ($) property	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds from sales of operating properties				$ 139	$ 126,460
Number of real estate properties | property				120
Seven Property Disposal
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties | property			7
Disposal group, including discontinued operation, assets			$ 103,000
Gain (loss) on sale of properties			$ 3,400
Shops at Otty
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	$ 200
Asset Impairment Charges						$ 1,600
Four Corner and Cornelius Gateway
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal		$ 600
Net proceeds from sales of operating properties		$ 44,900