Real Estate (Impairments) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Real Estate [Abstract]
Impairment losses, net of recoveries	$ 572	$ 1,028

Impairment Losses and Other Charges, Continuing Operations

No definition available.

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Namespace Prefix:	nnn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration