Significant Accounting Policies (Details 7) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
	May. 28, 2014 USD ($) property	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Discontinued Operations
Amount of retained proceeds from recently completed unsecured debt and mortgage debt as part of the spin-off					$ 1,003,135
Transaction Expenses
Discontinued operations transaction expenses					38,163
Transitional Services | Washington Prime Group Inc
Additional disclosures
Transition services fees earned		$ 1,400	$ 1,300	$ 4,300	1,800
Minimum | Washington Prime Group Inc
Additional disclosures
Annual fixed rate property management fees (as a percent)				2.50%
Maximum | Washington Prime Group Inc
Additional disclosures
Annual fixed rate property management fees (as a percent)				4.00%
Strip Center Business and Small Malls | Spinoff
Discontinued Operations
Number of properties merged under spin off into publicly traded REIT (Washington Prime Group Inc.) | property	98
Amount of retained proceeds from recently completed unsecured debt and mortgage debt as part of the spin-off	$ 1,000,000
Transaction Expenses
Discontinued operations transaction expenses					38,200	$ 38,200
Summarized financial information for discontinued operations
TOTAL REVENUE					262,652
Property Operating					43,175
Depreciation and amortization					76,992
Real estate taxes					32,474
Repairs and maintenance					10,331
Advertising and promotion					3,340
Provision for credit losses					1,494
Other					2,028
Total operating expenses					169,834
OPERATING INCOME					92,818
Interest expense					(26,076)
Income and other taxes					(112)
Income from unconsolidated entities					652
Gain upon acquisition of controlling interests and sale or disposal of assets and interest in unconsolidated entities, net					242
CONSOLIDATED NET INCOME					67,524
Net income attributable to noncontrolling interests					9,781
NET INCOME ATTRIBUTABLE TO UNITHOLDERS					57,743
Additional disclosures
Capital expenditures on a cash basis					$ 31,900
Strip Center Business and Small Malls | Spinoff | Washington Prime Group Inc
Additional disclosures
Term of property management agreement	2 years
Renewal term of property management agreement	1 year
Termination period of property management agreement	2 years
Period of prior written notice for termination of property management agreement	180 days
Termination period of transition services agreement	2 years
Minimum notice period for transition services agreement	180 days
Minimum notice period as percentage of original service period	50.00%
Exchange ratio of common shares for entity's stockholders to receive under spin off	0.50
Strip Center Business and Small Malls | Spinoff | Washington Prime Group LP
Additional disclosures
Exchange ratio of common units for entity's stockholders to receive under spin off	0.50