Schedule IV (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Face Amount of Mortgages	$ 26,190,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	22,815,000	[1],[2]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Mortgage Loans on Real Estate, Federal Income Tax Basis	22,815		21,138		34,707
Payments to Acquire Mortgage Notes Receivable	8,098		6,302		2,259
Movement in Mortgage Loans on Real Estate [Roll Forward]
Mortgage Loans on Real Estate, Beginning	21,138,000		34,707,000		35,993,000
Mortgage Loans on Real Estate, New Mortgage Loans	8,098,000	[3]	6,302,000	[3]	2,259,000	[3]
Mortgage Loans on Real Estate, Collections of Principal	(6,421,000)		(7,148,000)		(3,545,000)
Mortgage Loans on Real Estate, Foreclosures	0		(12,723,000)		0
Mortgage Loans on Real Estate, Ending	22,815,000		21,138,000		34,707,000
Paramus, NJ [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	9.00%
Mortgage Loans on Real Estate, Final Maturity Date	Feb. 01, 2022
Mortgage Loans on Real Estate, Periodic Payment Terms, Level Payments	(b)	[4]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	6,000,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	4,700,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Des Moines, IA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	8.00%
Mortgage Loans on Real Estate, Final Maturity Date	Oct. 15, 2013
Mortgage Loans on Real Estate, Periodic Payment Terms, Level Payments	(d)	[5]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	400,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	242,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Cleveland, OH [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	10.00%
Mortgage Loans on Real Estate, Final Maturity Date	Oct. 01, 2028
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(f)	[6]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	6,644,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	4,827,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Milford, CT [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	6.00%
Mortgage Loans on Real Estate, Final Maturity Date	Jun. 30, 2016
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(c)	[7]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	1,550,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	1,550,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Hollywood, FL [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	6.00%
Mortgage Loans on Real Estate, Final Maturity Date	Apr. 28, 2013
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(c)	[7]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	450,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	450,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Lodi, CA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	5.281%
Mortgage Loans on Real Estate, Final Maturity Date	Mar. 01, 2028
Mortgage Loans on Real Estate, Periodic Payment Terms, Level Payments	(f)	[6]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	338,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	338,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
California City, CA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	9.50%
Mortgage Loans on Real Estate, Final Maturity Date	Aug. 10, 2014
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(e)	[8]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	1,454,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	1,454,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Somerset, PA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	9.50%
Mortgage Loans on Real Estate, Final Maturity Date	Nov. 19, 2013
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(e)	[8]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	919,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	919,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Sportslvania, VA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	9.50%
Mortgage Loans on Real Estate, Final Maturity Date	Nov. 19, 2013
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(e)	[8]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	813,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	813,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Bakersfield, CA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	9.50%
Mortgage Loans on Real Estate, Final Maturity Date	Aug. 10, 2014
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(e)	[8]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	780,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	780,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Delano, CA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	9.50%
Mortgage Loans on Real Estate, Final Maturity Date	Aug. 10, 2014
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(e)	[8]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	791,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	791,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
Farmersville, CA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	9.50%
Mortgage Loans on Real Estate, Final Maturity Date	Aug. 10, 2014
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(e)	[8]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	551,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	551,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	0
4 properties in FL and GA [Member]
Mortgage Loans On Real Estate [Line Items]
Mortgage Loans on Real Estate, Interest Rate	6.25%
Mortgage Loans on Real Estate, Final Maturity Date	Jan. 04, 2014
Mortgage Loans on Real Estate, Periodic Payment Terms, Varying Amounts	(f)	[6]
Mortgage Loans on Real Estate, Prior Liens	0
Mortgage Loans on Real Estate, Face Amount of Mortgages	5,500,000
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	5,400,000	[1]
Mortgage Loans on Real Estate, Principal Amount of Delinquent Loans	$ 0

[1] Mortgages held by NNN and its subsidiaries for federal income tax purposes for the years ended December 31, 2011, 2010 and 2009 were $22,815, $21,138 and $34,707, respectively.

[2] The following shows the changes in the carrying amounts of mortgage loans during the years: 2011 2010 2009 Balance at beginning of year$21,138 $34,707 $35,993 New mortgage loans8,098 (h) 6,302 (h) 2,259 (h) Deductions during the year: Collections of principal(6,421) (7,148) (3,545) Foreclosures— (12,723) — Balance at the close of year$22,815 $21,138 $34,707

[3] Mortgages totaling $8,098, $6,302 and $2,259, were accepted in connection with real estate transactions for the years ended December 31, 2011, 2010 and 2009, respectively.

[4] Principal and interest is payable at level amounts over the life of the loan.

[5] Principal and interest is payable at level amounts over the life of the loan with a principal balloon payment at maturity.

[6] Interest only payments are due monthly. Periodic principal payments are due over the course of the loan based on specific terms outlined in the loan agreement, with the remaining principal balance due at maturity.

[7] Interest only payments are due monthly. Principal is due at maturity.

[8] Principal and interest is payable in full on the earlier of (i) specific events as outlined in the loan agreement, or (ii) maturity date.