Schedule IV - Mortgage Loans on Real Estate (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2023		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Face Amount of Mortgages		$ 3,000
Carrying amount of mortgages		996	[1]	$ 1,521	$ 2,011	$ 2,468
Principal Amount of Loans Subject to Delinquent Principal or Interest		0
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Balance at beginning of year		1,521		2,011	2,468
New mortgage loans		0		0	0	3,000
Deductions during the year:
Collections of principal		(559)		(521)	(486)
Other: credit (losses) recoveries	[2]	34		31	29
Foreclosures		0		0	0
Balance at the close of year		996	[1]	1,521	2,011	2,468
Mortgages held, federal income tax basis		1,002		1,530	2,011
Mortgages accepted in connection with real estate transactions		$ 0		$ 0	$ 0	$ 3,000
2 properties in VA
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Line Items]
Interest Rate		7.00%
Face Amount of Mortgages		$ 3,000
Carrying amount of mortgages	[1]	996
Principal Amount of Loans Subject to Delinquent Principal or Interest		0
Deductions during the year:
Balance at the close of year	[1]	$ 996

[1] Mortgages held by NNN and its subsidiaries for federal income tax purposes for the year ended December 31, 2023, 2022 and 2021 were $1,002, $1,530 and $2,011, respectively.

[2] In accordance with FASB ASC Topic 326, Financial Instruments - Credit Losses, NNN recorded an allowance for an estimated expected lifetime credit loss on its mortgage receivables based on the fair value of the collateral and the historical collectability trend analysis over 15 years.