Summary of Significant Accounting Policies - Organization and Principles of Consolidation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) joint_venture property retail_shopping_center shares	Dec. 31, 2015 USD ($) shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Prior Period Reclassification Adjustment	$ 47,300
Receivable with Imputed Interest, Effective Yield (Interest Rate)	7.00%
Operations Commenced Date	Dec. 31, 1993
Current Fiscal Year End Date	--12-31
General Partners' Capital Account, Units Outstanding | shares	104,497,286	97,213,000
Partners' Capital Account, Units | shares	104,651,456	97,367,000
Number Of Joint Ventures That Grant Each Partner A Right To Dissolve The Real Estate Partnership | joint_venture	5
Maximum Period Of TIme In Which Company Capitalizes Interest Costs	12 months
Tax Basis of Investments, Unrealized Appreciation (Depreciation), Net	$ 190,300	$ 183,900
Parent Company [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Parent Company, Ownership Percentage of Outstanding Common Partnership Units of Operating Partnership	99.90%	99.80%
Restricted Cash and Cash Equivalents	$ 4,623	$ 3,767
Wholly Owned Properties [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of Real Estate Properties | property	198
Unconsolidated Properties [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of Real Estate Properties | property	109
Partially Owned Properties [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of Real Estate Properties | retail_shopping_center	120
Consolidated Properties [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Number of Real Estate Properties | retail_shopping_center	11
Minimum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Equity Method Investment, Accretion Period	10 years
Maximum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Equity Method Investment, Accretion Period	40 years
Building and Improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Tenant Improvements [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Furniture and Fixtures [Member] | Minimum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Property, Plant and Equipment, Useful Life	7 years