Supplemental Disclosures of Cash Flow Information - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Mar. 28, 2019	Jan. 01, 2019	Apr. 30, 2018	Mar. 30, 2018
Supplemental Disclosures of Cash Flow Information
Cash paid for interest									$ 275,300	$ 251,500	$ 240,400
Interest capitalized to properties under development									751	369	461
Cash paid for income taxes									4,200	4,700	3,800
Non-cash activities
Lease liabilities	$ 122,285								122,285				$ 132,000
Right-of-use assets													$ 132,000
Additions to noncontrolling interest									11,370	18,848
Revenues	$ 397,529	$ 374,247	$ 365,450	$ 354,365	$ 342,576	$ 338,081	$ 328,886	$ 318,295	1,491,591	1,327,838	1,215,768
Mortgage loans assumed									$ 130,800
Acquisition of property using funds held in non-refundable escrow account										$ 7,500
Notes issued for acquisition of a portfolio of properties											$ 125,900
Realty Income, L.P.
Non-cash activities
Number of partnership units issued (in units)	89,322				373,797				89,322	373,797		89,322		131,790	242,007
Shares issued in conjunction with acquisitions									$ 6,300	$ 18,800
Noncontrolling interests
Non-cash activities
Additions to noncontrolling interest									11,370	18,848
Noncontrolling interests | Realty Income, L.P.
Non-cash activities
Additions to noncontrolling interest									6,286	18,848
Noncontrolling interests | Other Noncontrolling Interests
Non-cash activities
Additions to noncontrolling interest									$ 5,084	$ 0