Organization And Summary Of Significant Accounting Policies (Computation Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings attributable to NNN	$ 33,505	$ 21,303	$ 63,337		$ 42,123
Less: Excess of redemption value over carrying value of preferred shares redeemed	0	0	(3,098)		0
Net earnings available to NNN's common stockholders	27,579	19,607	52,334		38,731
Less: Earnings attributable to unvested restricted shares	(180)	(152)	(312)		(286)
Net earnings used in basic earnings per share	27,399	19,455	52,022		38,445
Reallocated undistributed income (loss)	0	0	0		0
Net earnings used in diluted earnings per share	27,399	19,455	52,022		38,445
Weighted average number of shares outstanding	107,006,399	85,309,082	106,321,014		84,635,929
Less: Unvested restricted stock	(696,804)	(647,468)	(631,329)		(612,375)
Less: Contingent shares	(317,581)	(251,826)	(272,090)		(251,826)
Weighted average number of shares outstanding used in basic earnings per share	105,992,014	84,409,788	105,417,595		83,771,728
Contingent shares	0	0	12,735		0
Convertible debt	1,310,445	160,006	1,259,319		346,699
Common stock options	1,419	3,162	1,855		3,305
Directors' deferred fee plan	155,115	153,012	152,576		149,620
Weighted average number of shares outstanding used in diluted earnings per share	107,458,993	84,725,968	106,844,080		84,271,352
Series C Depositary Share [Member]
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: Series C preferred stock dividends and Series D preferred stock dividends	0	(1,696)	(1,979)	[1]	(3,392)	[1]
Series D Depositary Share [Member]
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: Series C preferred stock dividends and Series D preferred stock dividends	$ (5,926)	$ 0	$ (5,926)	[2]	$ 0	[2]

[1] The Series C preferred stock was redeemed in March 2012. The dividends paid during the quarter ended March 31, 2012 include accumulated and unpaid dividends through the redemption date.

[2] The Series D preferred stock dividends paid during the quarter ended June 30, 2012 include accumulated and unpaid dividends from the issuance date through the declaration date. The Series D preferred stock has no maturity date and will remain outstanding unless redeemed.