Supplemental Disclosures of Cash Flow Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 item	Dec. 31, 2013 item	Dec. 31, 2012
Business Acquisitions
Loans receivable	$ 48,900,000
Number of acquired properties	5
Cash paid for interest	207,300,000	166,100,000	112,500,000
Interest capitalized to properties under development	444,000	537,000	498,000
Cash paid for income taxes	3,700,000	2,100,000	1,000,000
Non-cash investing and financing activities
Loans Assumed	166,700,000	81,300,000
Net premiums recorded on mortgages assumed	604,000	6,100,000
Interest rate swap agreement acquired	901,000
Real estate acquired in exchange of properties	11,600,000	7,400,000
Receivable recorded for the sale of an investment property as a result of an eminent domain action		1,900,000
Remaing receivable balance as a result of an eminent domain action		1,100,000
Number of investment properties sold as a result of an eminent domain action		2
Increase in Buildings and Improvements and Accounts Payable	4,000,000	5,500,000	3,800,000
Realty Income, L.P.
Business Acquisitions
Mortgage notes payable		32,400,000
Real estate acquired		55,900,000
Number of units issued		534,546
Cash		1,000,000
ARCT
Business Acquisitions
Real estate investments and related intangible assets		3,200,000,000
Other assets		19,500,000
Lines of credit payable		317,200,000
Term loan		235,000,000
Mortgage notes payable		539,000,000
Acquired lease intangible liabilities		79,700,000
Other liabilities		29,000,000
Noncontrolling interests		14,000,000
Real estate acquired		$ 3,200,000,000