Segment Information (Schedule Of Segment Reporting Information By Segment) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Segment Reporting Information [Line Items]
Earnings from continuing operations	$ 22,269	$ 20,065	$ 63,695	$ 56,524
Earnings including noncontrolling interests	22,608	21,194	64,731	59,143
Net earnings attributable to NNN	22,632	21,210	64,755	58,782
Total assets	3,146,361		3,146,361		2,713,575
NNN [Member] | Investment Assets [Member]
Segment Reporting Information [Line Items]
External revenues	68,027	56,749	192,441	169,544
Intersegment revenues	13	74	37	658
Earnings from continuing operations	22,364	20,076	64,069	56,428
Earnings including noncontrolling interests	22,632	21,210	64,755	58,791
Net earnings attributable to NNN	22,632	21,210	64,755	58,782
Total assets	3,274,997	2,750,581	3,274,997	2,750,581
NNN [Member] | Inventory Assets [Member]
Segment Reporting Information [Line Items]
External revenues	74	(114)	117	(2)
Intersegment revenues				534
Earnings from continuing operations	271	579	695	1,884
Earnings including noncontrolling interests	342	574	1,045	2,140
Net earnings attributable to NNN	366	590	1,069	1,788
Total assets	36,383	37,991	36,383	37,991
NNN [Member] | Eliminations (Intercompany) [Member]
Segment Reporting Information [Line Items]
Intersegment revenues	(13)	(74)	(37)	(1,192)
Earnings from continuing operations	(366)	(590)	(1,069)	(1,788)
Earnings including noncontrolling interests	(366)	(590)	(1,069)	(1,788)
Net earnings attributable to NNN	(366)	(590)	(1,069)	(1,788)
Total assets	(165,019)	(178,817)	(165,019)	(178,817)
NNN [Member]
Segment Reporting Information [Line Items]
External revenues	68,101	56,635	192,558	169,542
Earnings from continuing operations	22,269	20,065	63,695	56,524
Earnings including noncontrolling interests	22,608	21,194	64,731	59,143
Net earnings attributable to NNN	22,632	21,210	64,755	58,782
Total assets	$ 3,146,361	$ 2,609,755	$ 3,146,361	$ 2,609,755