Supplemental Disclosures of Cash Flow Information - Narrative (Details) - USD ($) $ in Thousands				12 Months Ended
	Mar. 28, 2019	Apr. 30, 2018	Mar. 30, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Supplemental Disclosures of Cash Flow Information
Cash paid for interest				$ 285,600	$ 275,300	$ 251,500
Cash paid for income taxes				13,100	4,200	4,700
Non-cash activities
Non-refundable deposits applied to acquisitions				13,800		7,500
Lease liabilities				114,559	122,285
Right-of-use assets				112,049	120,533
Additions to noncontrolling interest				3,168	11,370	18,848
Mortgage loans assumed					130,800
Noncontrolling interests
Non-cash activities
Additions to noncontrolling interest				3,168	$ 11,370	$ 18,848
Realty Income, L.P. units
Non-cash activities
Number of partnership units issued (in units)	89,322	131,790	242,007		89,322	373,797
Additions to noncontrolling interest					$ 6,300	$ 18,800
Realty Income, L.P. units | Noncontrolling interests
Non-cash activities
Additions to noncontrolling interest				0	6,286
Other Noncontrolling Interests | Noncontrolling interests
Non-cash activities
Additions to noncontrolling interest				3,168	$ 5,084
ASU 2016-02
Non-cash activities
Lease liabilities							$ 132,000
Right-of-use assets							$ 132,000
Derivative
Non-cash activities
Decrease in fair value of derivatives				$ 55,200