Noncontrolling Interests - Change in Carrying Value (Details) - USD ($) $ in Thousands				3 Months Ended		9 Months Ended
	Mar. 28, 2019	Apr. 30, 2018	Mar. 30, 2018	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period						$ 32,247
Contributions						2,106
Allocation of net income				$ 280	$ 239	865	$ 801
Carrying value at end of the period				$ 34,020		$ 34,020
Realty Income, L.P.
Change in the carrying value of all noncontrolling interests
Number of partnership units issued (in units)	89,322	131,790	242,007
Number of partnership units outstanding (in units)				463,119		463,119		463,119
Noncontrolling interests
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period						$ 32,247
Contributions						2,106
Distributions						(1,198)
Allocation of net income						865
Carrying value at end of the period				$ 34,020		34,020
Noncontrolling interests | Realty Income, L.P.
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period						24,100
Contributions						0
Distributions						(980)
Allocation of net income						749
Carrying value at end of the period				23,869		23,869
Noncontrolling interests | Other Noncontrolling Interests
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period						8,147
Contributions						2,106
Distributions						(218)
Allocation of net income						116
Carrying value at end of the period				$ 10,151		$ 10,151