Mortgages Payable (Details) (USD $)	Dec. 31, 2011		Dec. 31, 2010		Sep. 30, 2010
Debt Instrument [Line Items]
Interest Rate					8.50%
Outstanding Principal Balance	$ 23,171,000		$ 24,269,000
Mortgages [Member]
Debt Instrument [Line Items]
Carrying Value of Encumbered Assets	38,798,000	[1]
Outstanding Principal Balance	23,171,000	[1]	24,269,000	[1]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	19,290,000
Long-term Debt, Maturities, Repayments of Principal in Year Two	863,000
Long-term Debt, Maturities, Repayments of Principal in Year Three	881,000
Long-term Debt, Maturities, Repayments of Principal in Year Four	917,000
Long-term Debt, Maturities, Repayments of Principal in Year Five	952,000
Long-term Debt, Maturities, Repayments of Principal after Year Five	268,000
December 2001 - $623 [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Initial Balance	623,000	[2]
Interest Rate	9.00%
Carrying Value of Encumbered Assets	642,000	[1]
Outstanding Principal Balance	158,000		215,000
December 2001 - $698 [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Initial Balance	698,000	[2]
Interest Rate	9.00%
Carrying Value of Encumbered Assets	1,119,000	[1]
Outstanding Principal Balance	333,000		364,000
December 2001 - $485 [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Initial Balance	485,000	[2]
Interest Rate	9.00%
Carrying Value of Encumbered Assets	1,085,000	[1]
Outstanding Principal Balance	172,000		187,000
June 2002 - $21,000 [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Initial Balance	21,000,000	[3]
Interest Rate	6.90%	[3]
Carrying Value of Encumbered Assets	23,369,000	[1],[3]
Outstanding Principal Balance	18,488,000	[3]	18,841,000	[3]
February 2004 - $6,952 [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Initial Balance	6,952,000	[2]
Interest Rate	6.90%
Carrying Value of Encumbered Assets	11,280,000	[1]
Outstanding Principal Balance	3,485,000		4,038,000
March 2005 - $1,015 [Member] | Mortgages [Member]
Debt Instrument [Line Items]
Initial Balance	1,015,000	[2]
Interest Rate	8.14%
Carrying Value of Encumbered Assets	1,303,000	[1]
Outstanding Principal Balance	$ 535,000		$ 624,000

[1] Each loan is secured by a first mortgage lien on certain of NNN’s properties. The carrying values of the assets are as of December 31, 2011.

[2] Date entered represents the date that NNN acquired real estate subject to a mortgage securing a loan. The corresponding original principal balance represents the outstanding principal balance at the time of acquisition.

[3] NNN plans to use proceeds from the Credit Facility to repay outstanding indebtedness.