Organization and Summary of Significant Accounting Policies (Computation of Basic and Diluted Earnings per Share) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings attributable to NNN	$ 46,188	$ 45,571	$ 100,167		$ 88,904
Net earnings attributable to common stockholders	37,330	36,713	82,450		71,187
Less: Earnings allocated to unvested restricted shares	(176)	(198)	(340)		(361)
Net earnings used in basic and diluted earnings per share	$ 37,154	$ 36,515	$ 82,110		$ 70,826
Weighted average number of shares outstanding	134,163,959	123,495,650	133,313,523		122,957,186
Less: Unvested restricted stock	(420,417)	(489,095)	(404,463)		(446,439)
Less: Unvested contingent shares	(476,250)	(516,249)	(438,360)		(475,077)
Weighted average number of shares outstanding used in basic earnings per share	133,267,292	122,490,306	132,470,700		122,035,670
Other dilutive securities	333,364	342,218	354,100		357,061
Weighted average number of shares outstanding used in diluted earnings per share	133,600,656	122,832,524	132,824,800		122,392,731
Series D Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	$ (4,762)	$ (4,762)	$ (9,523)	[1]	$ (9,523)	[1]
Series E Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	$ (4,096)	$ (4,096)	$ (8,194)	[1]	$ (8,194)	[1]

[1] The Series D and E preferred stock have no maturity date and will remain outstanding unless redeemed.