Performance Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2011

Performance Incentive Plan [Abstract]

Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]

The following summarizes NNN’s stock-option compensation activity for each of the years ended December 31:

	Number of Shares
	2011		2010		2009
Outstanding, January 1	7,500		12,154		77,004
Options granted	—		—		—
Options exercised	(2,500	)	(4,654	)	(51,500	)
Options surrendered	—		—		(13,350	)
Outstanding, December 31	5,000		7,500		12,154
Exercisable, December 31	5,000		7,500		12,154

Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]

The following represents the weighted average option exercise price information for each of the years ended December 31:

	2011		2010		2009
Outstanding, January 1	$	14.11	$	13.72	$	14.00
Granted during the year	—		—		—
Exercised during the year	13.20		13.08		13.72
Outstanding, December 31	14.57		14.11		13.72
Exercisable, December 31	14.57		14.11		13.72

Schedule of Stock Options Outstanding and Exercisable [Table Text Block]

The following summarizes the outstanding options and the exercisable options at December 31, 2011:

	Total
Outstanding options:
Number of shares	5,000
Weighted-average exercise price	$	14.57
Weighted-average remaining contractual life in years	1.1
Exercisable options:
Number of shares	5,000
Weighted-average exercise price	$	14.57

Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block]

The following summarizes the restricted stock activity for the year ended December 31, 2011:

	Number of Shares		Weighted Average Share Price
Non-vested restricted shares, January 1	902,537		$	18.52
Restricted shares granted	141,351		24.45
Restricted shares vested	(135,396	)	20.24
Restricted shares forfeited	(5,215	)	20.96
Restricted shares repurchased	(2,704	)	26.50
Non-vested restricted shares, December 31	900,573		$	19.18

Schedule of Other Share-based Compensation, Activity [Table Text Block]

The following summarizes other grants made during the year ended December 31, 2011, pursuant to the 2007 Plan.

	Shares	Weighted Average   Share Price
Other share grants under the 2007 Plan:
Directors’ fees	9,632	$	25.91
Deferred Directors’ fees	26,312	25.86
	35,944	$	25.87
Shares available under the 2007 Plan for grant, end of period	4,690,814