Major Tenants Major Tenants (Details)	Dec. 31, 2012 tenant
Major Tenants [Abstract]
Number of tenants that contributed 10% or more of company rental and earned income	0

Number of Tenants That Contributed 10 Percent or More of Company Rental and Earned Income

No definition available.

Name:	nnn_NumberOfTenantsThatContributed10PercentOrMoreOfCompanyRentalAndEarnedIncome
Namespace Prefix:	nnn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant