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, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings attributable to NNN		$ 51,942	$ 46,188	$ 122,625	$ 100,167
Net earnings attributable to common stockholders		43,084	37,330	104,908	82,450
Less: Earnings allocated to unvested restricted shares		(177)	(176)	(326)	(340)
Net earnings used in basic and diluted earnings per share		$ 42,907	$ 37,154	$ 104,582	$ 82,110
Weighted average number of shares outstanding (in shares)		144,315,093	134,163,959	142,946,299	133,313,523
Less: Unvested restricted stock (in shares)		(406,170)	(420,417)	(374,701)	(404,463)
Less: Unvested contingent shares (in shares)		(465,548)	(476,250)	(429,608)	(438,360)
Weighted average number of shares outstanding used in basic earnings per share (in shares)		143,443,375	133,267,292	142,141,990	132,470,700
Other dilutive securities (in shares)		533,337	333,364	551,795	354,100
Weighted average number of shares outstanding used in diluted earnings per share (in shares)		143,976,712	133,600,656	142,693,785	132,824,800
Series D Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	[1]	$ (4,762)	$ (4,762)	$ (9,523)	$ (9,523)
Series E Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	[1]	$ (4,096)	$ (4,096)	$ (8,194)	$ (8,194)

[1] The Series D and E preferred stock have no maturity date and will remain outstanding unless redeemed. The earliest redemption date for the Series D and Series E preferred stock is February 2017 and May 2018, respectively.