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								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings attributable to NNN	$ 53,757	$ 47,940	$ 45,571	$ 43,333	$ 44,241	$ 44,352	$ 37,486	$ 34,066	$ 190,601	$ 160,145	$ 142,015
Less: Excess of redemption value over carrying value of Series C preferred shares redeemed									0	0	(3,098)
Net earnings attributable to common stockholders									155,167	132,222	121,489
Less: Earnings attributable to unvested restricted shares									(773)	(718)	(741)
Net earnings used in basic and diluted earnings per share									$ 154,394	$ 131,504	$ 120,748
Weighted average number of shares outstanding									125,221,358	118,969,771	107,873,577
Less: Unvested restricted shares									(467,968)	(448,590)	(654,127)
Less: Unvested contingent shares									(495,832)	(317,033)	(254,294)
Weighted average number of shares outstanding used in basic earnings per share									124,257,558	118,204,148	106,965,156
Convertible debt (in shares)									0	1,468,559	1,987,842
Other (in shares)									452,668	192,117	164,517
Weighted average number of shares outstanding used in diluted earnings per share									124,710,226	119,864,824	109,117,515