Mortgages Payable (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 item	Dec. 31, 2013 item	Dec. 31, 2012
Debt instrument
Remaining balance of deferred financing costs at period end	$ 23,274,000	$ 21,323,000
Mortgage Payable Balance	852,575,000	783,360,000
Maturity mortgages payable, excluding net premiums
2015	150,000,000
2016	275,000,000
2017	175,000,000
2018	350,000,000
2019	550,000,000
Thereafter	2,300,000,000
Totals	3,800,000,000
Minimum
Debt instrument
Weighted Average Stated Interest Rate (as a percent)	2.00%	2.50%
Weighted Average Effective Interest Rate (as a percent)	2.20%	2.40%
Maximum
Debt instrument
Weighted Average Stated Interest Rate (as a percent)	6.90%	6.90%
Weighted Average Effective Interest Rate (as a percent)	9.00%	9.20%
Mortgages Payable
Debt instrument
Amount repaid	85,200,000
Net discount (premiums) recorded upon assumption of mortgages	(604,000)	(28,400,000)
Deferred financing costs incurred		211,000	1,100,000
Remaining balance of deferred financing costs at period end	827,000	1,200,000
Number of Properties	241	227
Weighted Average Stated Interest Rate (as a percent)	5.00%	5.30%
Weighted Average Effective Interest Rate (as a percent)	4.00%	3.90%
Weighted Average Remaining Years Until Maturity	3 years 8 months 12 days	4 years 3 months 18 days
Principal Balance	836,011,000	754,508,000
Unamortized Premium Balance	(16,564,000)	(28,852,000)
Mortgage Payable Balance	852,575,000	783,360,000
Number of mortgages	57	47
Number of properties with mortgages	241	227
Assumed mortgages payable	166,700,000
Assumed mortgages payable, non-recourse	152,000,000
Maturity mortgages payable, excluding net premiums
2015	119,700,000
2016	248,400,000
2017	142,500,000
2018	15,100,000
2019	26,000,000
Thereafter	284,300,000
Totals	836,000,000
Mortgages repaid in full
Debt instrument
Number of mortgages repaid	6
Amount repaid	77,800,000
Mortgages, partial recourse
Debt instrument
Number of mortgages assumed subject to partial recourse by Realty Income	2
Assumed mortgages payable	14,700,000
Assumed mortgages payable, non-recourse	11,500,000
Assumed mortgages payable, full recourse	3,200,000
Variable rate mortgages
Debt instrument
Mortgage Payable Balance	$ 74,500,000	$ 31,100,000
Number of mortgages	5	2
Number of properties with mortgages	14