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, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Basic and Diluted Earnings:
Net earnings attributable to NNN	$ 58,028	$ 51,942	$ 131,685	$ 122,625
Net earnings attributable to common stockholders	49,447	43,084	101,068	104,908
Less: Earnings allocated to unvested restricted shares	(137)	(177)	(267)	(326)
Net earnings used in basic and diluted earnings per share	$ 49,310	$ 42,907	$ 100,801	$ 104,582
Basic and Diluted Weighted Average Shares Outstanding:
Weighted average number of shares outstanding (in shares)	149,119,191	144,315,093	148,354,604	142,946,299
Less: Unvested restricted stock (in shares)	(301,206)	(406,170)	(293,588)	(374,701)
Less: Unvested contingent restricted shares (in shares)	(445,484)	(465,548)	(405,940)	(429,608)
Weighted average number of shares outstanding used in basic earnings per share (in shares)	148,372,501	143,443,375	147,655,076	142,141,990
Other dilutive securities (in shares)	346,969	533,337	368,592	551,795
Weighted average number of shares outstanding used in diluted earnings per share (in shares)	148,719,470	143,976,712	148,023,668	142,693,785
Series D Preferred Stock
Basic and Diluted Earnings:
Less: preferred stock dividends	$ 0	$ (4,762)	$ (3,598)	$ (9,523)
Less: Excess of redemption value over carrying value of Series D preferred shares redeemed	0	0	(9,855)	0
Series E Preferred Stock
Basic and Diluted Earnings:
Less: preferred stock dividends	(4,096)	(4,096)	(8,194)	(8,194)
Series F Preferred Stock
Basic and Diluted Earnings:
Less: preferred stock dividends	$ (4,485)	$ 0	$ (8,970)	$ 0