Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) - USD ($)					3 Months Ended		9 Months Ended
	Sep. 01, 2015	Apr. 01, 2015	Dec. 03, 2014	Dec. 09, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Sep. 29, 2015	Aug. 10, 2015	Dec. 31, 2014
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Repayments of Secured Debt							$ 65,156,000	$ 9,528,000
Long-term Debt, Gross					$ 61,811,000		$ 61,811,000				$ 91,467,000
Line of Credit Facility, Expiration Date							Jan. 31, 2019
Long-term Line of Credit					16,225,000		$ 16,225,000				156,500,000
Revolving Credit Facility [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					500,000,000		500,000,000			$ 500,000,000
Long-term Line of Credit					$ 16,200,000		$ 16,200,000
Line of Credit Facility, Interest Rate During Period					1.20%		1.20%
Line of Credit Facility, Remaining Borrowing Capacity					$ 483,800,000		$ 483,800,000
Revolving Credit Facility [Member] | Accordion Feature [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					$ 1,000,000,000		$ 1,000,000,000
Loan Agreements [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Line of Credit Facility, Commitment Fee Percentage							0.20%
Line of Credit, Fronting Fee					0.125%		0.125%
Eurodollar [Member] | Loan Agreements [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Debt Instrument, Basis Spread on Variable Rate							1.00%
Federal Funds Rate [Member] | Loan Agreements [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Debt Instrument, Basis Spread on Variable Rate							0.50%
Renaissance Towne Centre Mortgage Note [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Repayments of Secured Debt		$ 16,100,000
Crossroads Shopping Center [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Repayments of Secured Debt	$ 48,300,000
Term Loan Agreement [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Debt Instrument, Face Amount									$ 300,000,000
Line of Credit Facility, Additional Borrowing Capacity									$ 200,000,000
Debt Instrument, Maturity Date							Jan. 31, 2019
Long-term Debt					$ 300,000,000		$ 300,000,000
Debt Instrument, Interest Rate, Effective Percentage					1.30%		1.30%
Term Loan Agreement [Member] | Federal Funds Effective Swap Rate [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Spread on Variable Rate							0.50%
Term Loan Agreement [Member] | Eurodollar [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Spread on Variable Rate							1.00%
Senior Notes 2024 [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			4.00%
Debt Instrument, Face Amount			$ 250,000,000		$ 250,000,000		$ 250,000,000				250,000,000
Debt Instrument, Maturity Date			Dec. 15, 2024
Interest Expense, Debt					2,500,000		7,500,000
Amortization of Debt Discount (Premium)					72,000		215,000
Deferred Finance Costs, Gross			$ 2,200,000
Senior Notes 2023 [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				5.00%
Debt Instrument, Face Amount				$ 250,000,000	250,000,000		250,000,000				$ 250,000,000
Debt Instrument, Maturity Date				Dec. 15, 2023
Interest Expense, Debt					3,100,000	$ 3,100,000	9,400,000	9,300,000
Amortization of Debt Discount (Premium)					87,000	$ 84,000	256,000	$ 245,000
Deferred Finance Costs, Gross				$ 2,600,000
Diamond Hills Plaza [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Long-term Debt, Gross					$ 35,500,000		$ 35,500,000
Debt Instrument, Interest Rate, Stated Percentage					3.55%		3.55%
Diamond Hills Plaza [Member] | PNC Bank, National Association [Member] | Secured Debt [Member]
Note 4 - Mortgage Notes Payable, Credit Facilities and Senior Notes (Details) [Line Items]
Long-term Debt, Gross	$ 35,500,000
Debt Instrument, Interest Rate, Stated Percentage	3.55%
Debt Instrument, Amortization Period	30 years