UNSECURED BANK CREDIT FACILITIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Line of Credit Facility [Line Items]
Weighted average interest rates (in hundredths)	1.87%	1.61%
Weighted average interest rate (including amortization of loan costs)	2.23%	2.01%
Notes payable to banks	$ 88,952,000	$ 76,160,000
Average bank borrowings	112,971,000	85,113,000
Amortization of bank loan costs	410,000	342,000	300,000
Former seven bank group unsecured revolving credit facility [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility available borrowings	200,000,000
Nine bank group unsecured revolving credit facility [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility available borrowings	225,000,000
Unsecured revolving credit facility maturity date	January 2017
Debt instrument, spread above LIBOR variable rate (in basis points)	117.5
Line of credit, facility fee (in basis points)	22.5
Banks included in the unsecured revolving credit facility group	9
Line of Credit Facility, Interest Rate at Period End	1.343%
Notes payable to banks	85,000,000
Extension option on credit facility	1 year
Expansion option on credit facility	100,000,000
Line of Credit Facility, Additional Borrowing Capacity	140,000,000
Former Pnc na revolving credit facility [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility available borrowings	25,000,000
PNC N.A. unsecured revolving credit facility [Member]
Line of Credit Facility [Line Items]
Unsecured revolving credit facility available borrowings	25,000,000
Unsecured revolving credit facility maturity date	January 2017
Debt instrument, spread above LIBOR variable rate (in basis points)	117.5
Line of credit, facility fee (in basis points)	22.5
Line of Credit Facility, Interest Rate at Period End	1.343%
Notes payable to banks	3,952,000
Additional remaining line of credit	$ 21,048,000
Extension option on credit facility	1 year