CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Rental income from operating leases	$ 602,131,000	$ 565,405,000	$ 512,883,000
Earned income from direct financing leases	923,000	978,000	1,336,000
Percentage rent	1,561,000	1,700,000	1,735,000
Real estate expense reimbursement from tenants	16,784,000	15,512,000	14,984,000
Interest and other income from real estate transactions	1,262,000	1,338,000	2,709,000
Total revenues	622,661,000	584,933,000	533,647,000
Operating expenses:
General and administrative	34,248,000	33,805,000	36,508,000
Real estate	25,099,000	23,105,000	20,852,000
Depreciation and amortization	174,398,000	173,720,000	149,101,000
Impairment – commercial mortgage residual interests valuation	0	0	6,830,000
Impairment losses – real estate and other charges, net of recoveries	28,211,000	8,955,000	11,287,000
Retirement severance costs	1,013,000	7,845,000	0
Total operating expenses	262,969,000	247,430,000	224,578,000
Gain on disposition of real estate	65,070,000	36,655,000	27,182,000
Earnings from operations	424,762,000	374,158,000	336,251,000
Other expenses (revenues):
Interest and other income	(1,810,000)	(322,000)	(170,000)
Interest expense	115,847,000	109,109,000	96,352,000
Real estate acquisition costs	0	0	563,000
Loss on early extinguishment of debt	18,240,000	0	0
Total other expenses (revenues)	132,277,000	108,787,000	96,745,000
Net earnings	292,485,000	265,371,000	239,506,000
Earnings attributable to noncontrolling interests	(38,000)	(398,000)	(6,000)
Net earnings attributable to NNN	292,447,000	264,973,000	239,500,000
Net earnings available to common stockholders	$ 258,120,000	$ 217,193,000	$ 200,877,000
Net earnings per share of common stock:
Basic (in dollars per share)	$ 1.65	$ 1.45	$ 1.39
Diluted (in dollars per share)	$ 1.65	$ 1.45	$ 1.38
Weighted average number of common shares outstanding:
Basic (in shares)	155,744,601	149,111,188	144,176,224
Diluted (in shares)	156,295,619	149,432,641	144,660,633
Other comprehensive income:
Net earnings attributable to NNN	$ 292,447,000	$ 264,973,000	$ 239,500,000
Amortization of interest rate hedges	3,664,000	1,932,000	2,802,000
Fair value of forward starting swaps	4,080,000	(7,688,000)	13,345,000
Net loss – commercial mortgage residual interests	0	0	(4,454,000)
Net gain – available-for-sale securities	298,000	209,000	468,000
Comprehensive income attributable to NNN	300,489,000	259,426,000	251,661,000
Series D Preferred Stock
Other expenses (revenues):
Preferred stock dividends	0	(3,598,000)	(19,047,000)
Excess of redemption value over carrying value of Series D preferred shares redeemed	0	(9,855,000)	0
Series E Preferred Stock
Other expenses (revenues):
Preferred stock dividends	(16,387,000)	(16,387,000)	(16,387,000)
Series F Preferred Stock
Other expenses (revenues):
Preferred stock dividends	$ (17,940,000)	$ (17,940,000)	$ (3,189,000)