Notes Payable (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 instrument		Dec. 31, 2013	Sep. 30, 2007		Jul. 31, 2011 derivative	Apr. 30, 2013 derivative	May 31, 2014 derivative	Jun. 30, 2014
Notes Payable [Line Items]
Discount	$ 10,285,000		$ 10,816,000
Number of Interest Rate Derivatives Held	0
Debt Issuance Costs Incurred	15,500,000
Interest Rate Swap
Notes Payable [Line Items]
Notional amount				100,000,000
Liability amount from termination of hedge agreement				3,260,000	[1]
Liability amount from termination of hedge agreement, comprehensive income				3,228,000	[2]
2015 Notes
Notes Payable [Line Items]
Principal	150,000,000	[3],[4]
Discount	390,000	[3],[4]
Net Price	149,610,000	[3],[4]
Stated Rate	6.15%	[3],[4]
Effective Rate	6.185%	[3],[4],[5]
2017 Notes
Notes Payable [Line Items]
Principal	250,000,000	[3],[6]
Discount	877,000	[3],[6]
Net Price	249,123,000	[3],[6]
Stated Rate	6.875%	[3],[6]
Effective Rate	6.924%	[3],[5],[6]
2017 Notes | Interest Rate Swap
Notes Payable [Line Items]
Notional amount				100,000,000
Liability amount from termination of hedge agreement				3,260,000
Liability amount from termination of hedge agreement, comprehensive income				3,228,000
2021 Notes
Notes Payable [Line Items]
Principal	300,000,000	[3],[7]
Discount	4,269,000	[3],[7]
Net Price	295,731,000	[3],[7]
Stated Rate	5.50%	[3],[7]
Effective Rate	5.69%	[3],[5],[7]
2021 Notes | Interest Rate Swap
Notes Payable [Line Items]
Notional amount						150,000,000
Liability amount from termination of hedge agreement						5,300,000
Liability amount from termination of hedge agreement, comprehensive income						5,218,000
Number of Interest Rate Derivatives Held						2
2022 Notes
Notes Payable [Line Items]
Principal	325,000,000	[3]
Discount	4,989,000	[3]
Net Price	320,011,000	[3]
Stated Rate	3.80%	[3]
Effective Rate	3.984%	[3],[5]
2023 Notes
Notes Payable [Line Items]
Principal	350,000,000	[3],[8]
Discount	2,594,000	[3],[8]
Net Price	347,406,000	[3],[8]
Stated Rate	3.30%	[3],[8]
Effective Rate	3.388%	[3],[5],[8]
2023 Notes | Forward Starting Swaps
Notes Payable [Line Items]
Notional amount							240,000,000
Liability amount from termination of hedge agreement							3,156,000
Liability amount from termination of hedge agreement, comprehensive income							3,141,000
Number of Interest Rate Derivatives Held							4
2024 Notes
Notes Payable [Line Items]
Principal	350,000,000	[3],[9]
Discount	707,000	[3],[9]
Net Price	349,293,000	[3],[9]
Stated Rate	3.90%	[3],[9]
Effective Rate	3.924%	[3],[5],[9]
2024 Notes | Forward Starting Swaps
Notes Payable [Line Items]
Notional amount								225,000,000
Liability amount from termination of hedge agreement								6,312,000
Number of Interest Rate Derivatives Held								3
2012 Notes
Notes Payable [Line Items]
Principal									$ 150,000,000
Stated Rate									6.25%

[1] Liability

[2] The amount reported in accumulated other comprehensive income will be reclassified to interest expense as interest payments are made on the related notes payable.

[3] The note discounts are amortized to interest expense over the respective term of each debt obligation using the effective interest method.

[4] NNN plans to use proceeds from the Credit Facility and/or potential debt or equity offerings to repay the outstanding indebtedness.

[5] Includes the effects of the discount, treasury lock gain/loss and swap gain/loss, as applicable.

[6] NNN entered into an interest rate hedge with a notional amount of $100,000. Upon issuance of the 2017 Notes, NNN terminated the interest rate hedge agreement resulting in a liability of $3,260, of which $3,228 was recorded to other comprehensive income. The liability has been deferred and is being amortized as an adjustment to interest expense over the term of the 2017 Notes using the effective interest method.

[7] NNN entered into two interest rate hedges with a total notional amount of $150,000. Upon issuance of the 2021 Notes, NNN terminated the interest rate hedge agreements resulting in a liability of $5,300, of which $5,218 was deferred in other comprehensive income. The deferred liability is being amortized over the term of the note using the effective interest method.

[8] NNN entered into four forward starting swaps with an aggregate notional amount of $240,000. Upon issuance of the 2023 Notes, NNN terminated the forward starting swaps resulting in a liability of $3,156, of which $3,141 was deferred in other comprehensive income. The deferred liability is being amortized over the term of the note using the effective interest method.

[9] NNN entered into three forward starting swaps with an aggregate notional amount of $225,000. Upon issuance of the 2024 Notes, NNN terminated the forward starting swaps resulting in a liability of $6,312, which was deferred in other comprehensive income. The deferred liability is being amortized over the term of the note using the effective interest method.