Transactions with Related Parties (Details Textual) (USD $)	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Percentage of property management fee	4.50%
Percentage of oversight fee	1.00%
Transaction with Related Parties (Textual) [Abstract]
Percentage of Gross Income Generated Property		2.50%
Percentage Of Gross Income Generated By Multi-Tenant Industrial Property		4.00%
Percentage Of Gross Income Generated By Multi-Family Property		3.75%
Percentage Of Gross Income Generated By Multi-Tenant Office Property		3.75%
Percentage Of Gross Income Generated By Multi-Tenant Retail Property		4.50%
Percentage Of Gross Income Generated By Single-Tenant Industrial Property		2.25%
Percentage Of Gross Income Generated By Single-Tenant Office Property		2.90%
Percentage Of Gross Income Generated By Single-Tenant Retail Property		2.90%
Reimbursement to property managers		$ 14,049,000	$ 15,752,000	$ 14,626,000
Non-cumulative, non-compounded return on invested capital		5.00%
Percentage of Annual business management fee		1.00%
Payment of management fee to Business Manager, percentage of average invested assets		0.25%
Average invested assets		11,470,745,000	11,515,550,000	11,411,953,000
Business management fee, percent type		0.35%	0.35%	0.32%
Investigation Costs		0
Payment to related party		0.20%
Business management fee		39,892,000	40,000,000	36,000,000
Inland Bank and Trust [Member]
Transaction with Related Parties (Textual) [Abstract]
Deposited in Inland Bank and Trust		375,000	373,000
Captive [Member]
Transaction with Related Parties (Textual) [Abstract]
Insurance Premiums Paid		12,217,000	9,627,000	10,096,000
Inland Real Estate Corporation [Member]
Transaction with Related Parties (Textual) [Abstract]
Shares held in related entity		889,820	889,820
Equity interest in related entity		$ 7,540,000	$ 6,848,000
Triple Net Lease Properties [Member]
Related Party Transaction [Line Items]
Fee Expenses Percentage of Gross Operating Income	2.90%
Bank Branches [Member]
Related Party Transaction [Line Items]
Fee Expenses Percentage of Gross Operating Income	2.50%