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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period						$ 29,702
Reallocation of equity				$ 0	$ 0	0	$ 0
Allocation of net income				239	226	801	$ 740
Carrying value at end of the period				$ 29,261		$ 29,261
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				89,322
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						$ 29,702
Reallocation of equity				$ (47)	$ 653	(47)	$ 653
Distributions						(1,195)
Allocation of net income						801
Carrying value at end of the period				29,261		29,261
Noncontrolling interests | Realty Income, L.P.
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period						24,596
Reallocation of equity						(47)
Distributions						(972)
Allocation of net income						672
Carrying value at end of the period				24,249		24,249
Noncontrolling interests | Other Noncontrolling Interests
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period						5,106
Reallocation of equity						0
Distributions						(223)
Allocation of net income						129
Carrying value at end of the period				$ 5,012		$ 5,012