Segment Information (Schedule Of Segment Reporting Information By Segment) (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Earnings from continuing operations	$ 21,139	$ 20,963	$ 41,865	$ 37,046
Earnings including noncontrolling interests	21,269	21,650	42,123	37,948
Net earnings attributable to NNN	21,303	21,206	42,123	37,571
Total assets	2,798,807		2,798,807		2,713,575
NNN [Member] | Investment Assets [Member]
External revenues	62,881	56,928	125,134	113,632
Intersegment revenues	12	285	25	584
Earnings from continuing operations	21,320	20,742	42,144	36,940
Earnings including noncontrolling interests	21,303	21,308	42,123	37,580
Net earnings attributable to NNN	21,303	21,206	42,123	37,571
Total assets	2,929,244	2,725,655	2,929,244	2,725,655
NNN [Member] | Inventory Assets [Member]
External revenues		70	42	112
Intersegment revenues		275		533
Earnings from continuing operations	366	1,036	424	1,304
Earnings including noncontrolling interests	513	1,157	703	1,566
Net earnings attributable to NNN	547	815	703	1,198
Total assets	38,365	43,915	38,365	43,915
NNN [Member] | Eliminations (Intercompany) [Member]
Intersegment revenues	(12)	(560)	(25)	(1,117)
Earnings from continuing operations	(547)	(815)	(703)	(1,198)
Earnings including noncontrolling interests	(547)	(815)	(703)	(1,198)
Net earnings attributable to NNN	(547)	(815)	(703)	(1,198)
Total assets	(168,802)	(182,172)	(168,802)	(182,172)
NNN [Member]
External revenues	62,881	56,998	125,176	113,744
Earnings from continuing operations	21,139	20,963	41,865	37,046
Earnings including noncontrolling interests	21,269	21,650	42,123	37,948
Net earnings attributable to NNN	21,303	21,206	42,123	37,571
Total assets	$ 2,798,807	$ 2,587,398	$ 2,798,807	$ 2,587,398