Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2019
Financial Instruments, Owned, at Fair Value [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments:NNN believes the carrying value of its Credit Facility approximates fair value based upon its nature, terms and variable interest rate. NNN believes that the carrying value of its mortgages payable at March 31, 2019 and December 31, 2018, approximate fair value based upon current market prices of comparable instruments (Level 3). At March 31, 2019 and December 31, 2018, the fair value of NNN’s notes payable net of unamortized discount and excluding debt costs was $2,914,825,000 and $2,813,583,000, respectively, based upon quoted market prices, which is a Level 1 valuation since NNN's notes payable are publicly traded.