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
	Mar. 31, 2015		Mar. 31, 2014
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Net earnings attributable to NNN	$ 53,978		$ 43,333
Net earnings attributable to common stockholders	45,119		34,474
Less: Earnings allocated to unvested restricted shares	(163)		(163)
Net earnings used in basic and diluted earnings per share	44,956		34,311
Weighted average number of shares outstanding	132,453,638		122,412,739
Less: Unvested restricted stock	(388,331)		(403,309)
Less: Unvested contingent shares	(400,049)		(433,447)
Weighted average number of shares outstanding used in basic earnings per share	131,665,258		121,575,983
Other dilutive securities	444,707		290,968
Weighted average number of shares outstanding used in diluted earnings per share	132,109,965		121,866,951
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)	[1]	(4,762)	[1]
Series E Preferred Stock
Earnings Per Share, Basic and Diluted, by Common Class, Including Two Class Method [Line Items]
Less: preferred stock dividends	$ (4,097)	[1]	$ (4,097)	[1]

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