Condensed Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Series C Depositary Share [Member]	Sep. 30, 2011 Series C Depositary Share [Member]	Sep. 30, 2012 Series D Depositary Share [Member]	Sep. 30, 2011 Series D Depositary Share [Member]
Cash flows from operating activities:
Earnings including noncontrolling interests	$ 101,290	$ 64,731
Adjustments to reconcile net earnings to net cash provided by operating activities:
Performance incentive plan expense	7,010	5,057
Depreciation and amortization	54,926	42,802
Impairment losses and other charges	9,043	431
Impairment - commercial mortgage residual interests valuation	2,718	396
Amortization of notes payable discount	3,641	5,032
Amortization of debt costs	2,506	0
Amortization of mortgages payable premium	(14)	0
Amortization of deferred interest rate hedges	171	(47)
Equity in earnings of unconsolidated affiliate	(4,074)	(321)
Distributions received from unconsolidated affiliate	7,019	432
Gain on disposition of real estate portfolio	(4,446)	(140)
Gain on note receivable and property foreclosure	(198)	0
Other	0	266
Change in operating assets and liabilities, net of assets acquired and liabilities assumed in business combinations:
Additions to held for sale real estate	(4,941)	(790)
Proceeds from disposition of held for sale real estate	0	1,058
Decrease in real estate leased to others using the direct financing method	1,222	1,191
Increase in work in process	(1,225)	(856)
Decrease in mortgages, notes and accrued interest receivable	37	170
Decrease in receivables	1,014	1,734
Decrease (increase) in commercial mortgage residual interests	286	(204)
Decrease (increase) in accrued rental income	(695)	93
Decrease in other assets	1,365	571
Increase in accrued interest payable	7,004	15,029
Increase (decrease) in other liabilities	(4,893)	1,548
Increase (decrease) in current tax liability	(7,192)	962
Net cash provided by operating activities	171,574	139,145
Cash flows from investing activities:
Proceeds from the disposition of real estate, Investment Portfolio	32,371	8,138
Additions to real estate:
Accounted for using the operating method	(414,843)	(434,532)
Accounted for using the direct financing method	0	(1,747)
Increase in mortgages and notes receivable	(8,768)	(5,706)
Principal payments on mortgages and notes receivable	10,668	4,938
Payment of lease costs	(1,583)	(862)
Return of investment from unconsolidated affiliate	1,220	0
Other	(313)	(2,191)
Net cash used in investing activities	(381,248)	(431,962)
Cash flows from financing activities:
Proceeds from line of credit payable	685,900	504,800
Repayment of line of credit payable	(751,500)	(665,800)
Payment of interest rate hedge	0	(5,300)
Proceeds from notes payable	320,011	295,731
Repayment of notes payable	(50,000)	0
Payment of debt costs	(2,992)	(5,464)
Repayment of mortgages payable	(19,134)	(816)
Proceeds from issuance of common stock	119,259	299,528
Proceeds from issuance of preferred stock	287,500	0
Redemption of preferred stock	(92,000)	0
Payment of Series C and Series D preferred stock dividends			(1,979)	(5,089)	(10,688)	0
Payment of common stock dividends	(124,139)	(96,915)
Noncontrolling interest distributions	0	(45)
Noncontrolling interest contributions	0	41
Stock issuance costs	(11,200)	(10,224)
Net cash provided by financing activities	349,038	310,447
Net increase in cash and cash equivalents	139,364	17,630
Cash and cash equivalents at beginning of year	2,082	2,048
Cash and cash equivalents at end of year	141,446	19,678
Supplemental disclosure of cash flow information:
Interest paid, net of amount capitalized	50,872	37,117
Taxes paid (received)	125	(541)
Supplemental disclosure of non-cash investing and financing activities:
Issued 396,577 and 141,351 shares of restricted and unrestricted common stock in 2012 and 2011, respectively, pursuant to NNN's performance incentive plan	8,576	3,456
Issued 12,373 and 6,975 shares of common stock in 2012 and 2011, respectively, to directors pursuant to NNN’s performance incentive plan	346	177
Issued 14,836 and 19,962 shares of common stock in 2012 and 2011, respectively, pursuant to NNN’s Deferred Director Fee Plan	223	338
Surrender of 4,712 and of 5,215 shares of restricted common stock in 2012 and 2011, respectively	113	109
Change in other comprehensive income	(382)	(4,701)
Change in lease classification (direct financing lease to operating lease)	757	3,407
Mortgage payable assumed in connection with real estate transaction	6,634	0
Real estate acquired in connection with mortgage receivable foreclosure	490	0
Real estate received in note receivable foreclosure	$ 1,595	$ 0