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Organization and Summary of Significant Accounting Policies (Summary of NNN's Investment Portfolio) (Details)
 3 Months Ended
Mar. 31, 2017
ft²
state
property
Accounting Policies [Abstract]  
Total properties | property 2,543
Gross leasable area (square feet) | ft² 27,311,000
States | state 48
Weighted average remaining lease term (years) 11 years 5 months