Organization and Summary of Significant Accounting Policies (Computation of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Basic and Diluted Earnings:
Net earnings attributable to NNN		$ 66,092	$ 50,784	$ 51,942	$ 70,683	$ 42,471	$ 55,198	$ 46,188	$ 53,978	$ 239,500		$ 197,836	$ 190,601
Net earnings attributable to common stockholders										200,877		162,402	155,167
Less: Earnings attributable to unvested restricted shares										(695)		(706)	(773)
Net earnings used in basic and diluted earnings per share										$ 200,182		$ 161,696	$ 154,394
Basic and Diluted Weighted Average Shares Outstanding:
Weighted average number of shares outstanding (in shares)										145,014,422		134,868,640	125,221,358
Less: Unvested restricted shares (in shares)										(390,522)		(412,505)	(467,968)
Less: Unvested contingent restricted shares (in shares)										(447,676)		(457,461)	(495,832)
Weighted average number of shares outstanding used in basic earnings per share (in shares)										144,176,224		133,998,674	124,257,558
Effects of dilutive securities:
Other (shares)										484,409		490,742	452,668
Weighted average number of shares outstanding used in diluted earnings per share (in shares)										144,660,633		134,489,416	124,710,226
Series D Preferred Stock
Basic and Diluted Earnings:
Preferred stock dividends	[1]									$ (19,047)		$ (19,047)	$ (19,047)
Series E Preferred Stock
Basic and Diluted Earnings:
Preferred stock dividends	[2]									(16,387)		(16,387)	(16,387)
Series F Preferred Stock
Basic and Diluted Earnings:
Preferred stock dividends										$ (3,189)	[3]	$ 0	$ 0

[1] In January 2017, NNN called for redemption of all outstanding shares of its Series D Preferred Stock represented by depositary shares, each representing a 1/100th interest in a Series D Preferred Stock share. The depositary shares will be redeemed on February 23, 2017.

[2] The Series E Preferred Stock has no maturity date and will remain outstanding unless redeemed by NNN. The earliest redemption date for the Series E Preferred Stock is May 2018.

[3] The Series F Preferred Stock was issued October 11, 2016 and has no maturity date and will remain outstanding unless redeemed by NNN. The earliest redemption date for the Series F preferred stock is October 2021.