Dividends (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
		Jan. 17, 2017	Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Payment of common stock dividends (in USD per share)			$ 1.78		$ 1.71	$ 1.65
Payment of common stock dividends, declared and paid			$ 257,007		$ 228,699	$ 204,157
Common stock (in dollars per share)			$ 1.78		$ 1.71	$ 1.65
Subsequent Event
Class of Stock [Line Items]
Common stock (in dollars per share)		$ 0.455
Series E Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[1]		$ 1.425		$ 1.425	$ 1.425
Preferred stock dividends	[1]		$ 16,387		$ 16,387	$ 16,387
Series D Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[2]		$ 1.65625		$ 1.65625	$ 1.65625
Preferred stock dividends	[2]		$ 19,047		$ 19,047	$ 19,047
Series F Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[3]		$ 0.231111
Preferred stock dividends			$ 3,189	[3]	$ 0	$ 0
Ordinary dividends
Class of Stock [Line Items]
Payment of common stock dividends (in USD per share)			$ 1.513705		$ 1.363294	$ 1.306992
Ordinary dividends | Series E Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[1]		1.425000		1.385670	1.393700
Ordinary dividends | Series D Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[2]		1.656250		1.610538	1.619870
Ordinary dividends | Series F Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[3]		0.231111
Qualified dividends
Class of Stock [Line Items]
Payment of common stock dividends (in USD per share)			0		0.019005	0.006212
Qualified dividends | Series E Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[1]		0		0.020141	0.005738
Qualified dividends | Series D Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[2]		0		0.023409	0.006670
Qualified dividends | Series F Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[3]		0
Capital gain
Class of Stock [Line Items]
Payment of common stock dividends (in USD per share)			0		0.007806	0.008603
Capital gain | Series E Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[1]		0		0.007937	0.009177
Capital gain | Series D Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[2]		0		0.009225	0.010666
Capital gain | Series F Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[3]		0
Unrecaptured Section 1250 Gain
Class of Stock [Line Items]
Payment of common stock dividends (in USD per share)			0		0.011055	0.015362
Unrecaptured Section 1250 Gain | Series E Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[1]		0		0.011252	0.016385
Unrecaptured Section 1250 Gain | Series D Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[2]		0		0.013078	0.019044
Unrecaptured Section 1250 Gain | Series F Preferred Stock
Class of Stock [Line Items]
Payment of preferred stock dividends (in USD per share)	[3]		0
Nontaxable distributions
Class of Stock [Line Items]
Payment of common stock dividends (in USD per share)			$ 0.266295		$ 0.308840	$ 0.312831

[1] 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.

[2] 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.

[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.