Subsequent Events (Details) (USD $)	6 Months Ended		6 Months Ended		0 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 2028 Notes [Member]		Jul. 11, 2013 Subsequent Event [Member] 2028 Notes [Member]
Subsequent Event [Line Items]
Principal amount of debt converted			$ 91,000	[1],[2],[3]	$ 130,000
Outstanding principal balance	$ 222,944,000	$ 238,572,000	$ 222,944,000	[1],[2],[3]	$ 222,814,000
Average Daily Closing Price, Rated, Period	20 days

[1] Debt issuance costs include underwriting discounts and commissions, legal and accounting fees, rating agency fees and printing expenses. These costs were deferred and amortized using the effective interest method and are fully amortized at June 30, 2013.

[2] NNN repurchased $11,000 in 2009 for a purchase price of $8,588 resulting in a gain of $1,867.

[3] The conversion rate per $1 principal amount was 39.5360 shares of NNN’s common stock, which is equivalent to a conversion price of $25.2934 per share of common stock.