Organization and Summary of Significant Accounting Policies (Computation of Basic and Diluted Earnings per Share) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Basic and Diluted Earnings:
Net earnings attributable to NNN	$ 61,120	$ 50,784	$ 192,805	$ 173,409
Net earnings attributable to common stockholders	52,538	41,925	153,606	146,833
Less: Earnings allocated to unvested restricted shares	(132)	(184)	(399)	(510)
Net earnings used in basic and diluted earnings per share	$ 52,406	$ 41,741	$ 153,207	$ 146,323
Basic and Diluted Weighted Average Shares Outstanding:
Weighted average number of shares outstanding (in shares)	150,076,348	146,982,759	148,934,825	144,301,606
Less: Unvested restricted stock (in shares)	(277,713)	(406,170)	(288,238)	(385,267)
Less: Unvested contingent restricted shares (in shares)	(457,610)	(465,548)	(423,353)	(441,675)
Weighted average number of shares outstanding used in basic earnings per share (in shares)	149,341,025	146,111,041	148,223,234	143,474,664
Other dilutive securities (in shares)	326,584	570,551	303,127	561,501
Weighted average number of shares outstanding used in diluted earnings per share (in shares)	149,667,609	146,681,592	148,526,361	144,036,165
Series D Preferred Stock
Basic and Diluted Earnings:
Less: preferred stock dividends	$ 0	$ (4,762)	$ (3,598)	$ (14,285)
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	(4,097)	(4,097)	(12,291)	(12,291)
Series F Preferred Stock
Basic and Diluted Earnings:
Less: preferred stock dividends	$ (4,485)	$ 0	$ (13,455)	$ 0