Organization and Summary of Significant Accounting Policies (Computation of Basic and Diluted Earnings per Share) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings attributable to NNN		$ 70,683	$ 53,978
Net earnings attributable to common stockholders		61,824	45,119
Less: Earnings allocated to unvested restricted shares		(151)	(163)
Net earnings used in basic and diluted earnings per share		$ 61,673	$ 44,956
Weighted average number of shares outstanding (in shares)		141,577,504	132,453,638
Less: Unvested restricted stock (in shares)		(343,466)	(388,331)
Less: Unvested contingent shares (in shares)		(393,667)	(400,049)
Weighted average number of shares outstanding used in basic earnings per share (in shares)		140,840,371	131,665,258
Other dilutive securities (in shares)		485,632	444,707
Weighted average number of shares outstanding used in diluted earnings per share (in shares)		141,326,003	132,109,965
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)
Series E Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	[1]	$ (4,097)	$ (4,097)

[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.