Noncontrolling Interests (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018 USD ($) shares	Mar. 31, 2017 USD ($)	Dec. 31, 2016 property item	Mar. 30, 2018 shares	Dec. 31, 2017 shares	Jun. 27, 2013 shares	Jan. 22, 2013 shares
Noncontrolling interests
Conversion ratio	1
Number of properties acquired | property			2
Number of joint ventures controlling interest acquired | item			2
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period	$ 19,207
Redemptions	(1,468)
Shares issued in conjunction with acquisition	12,144
Distributions	(356)
Allocation of net income	152	$ 165
Carrying value at end of the period	$ 29,679
Joint Venture One
Noncontrolling interests
Ownership interest (as a percent)	95.00%
Joint Venture Two
Noncontrolling interests
Ownership interest (as a percent)	74.00%
Tau Operating Partnership
Noncontrolling interests
Realty Income partnership units, ownership interest (as a percent)	99.40%
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period	$ 13,322
Distributions	(208)
Allocation of net income	77
Carrying value at end of the period	$ 13,191
Number of partnership units issued | shares							317,022
Number of partnership units outstanding | shares	317,022				317,022
Realty Income, L.P.
Noncontrolling interests
Third party partnership units, ownership interest (as a percent)	1.10%
Realty Income partnership units, ownership interest (as a percent)	98.90%
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period	$ 2,160
Redemptions	(1,468)
Shares issued in conjunction with acquisition	12,144
Distributions	(72)
Allocation of net income	55
Carrying value at end of the period	$ 12,819
Number of partnership units issued | shares	242,007			242,007		534,546
Number of partnership units outstanding | shares	270,189				88,182
Other Noncontrolling Interests
Change in the carrying value of all noncontrolling interests
Carrying value at beginning of the period	$ 3,725
Distributions	(76)
Allocation of net income	20
Carrying value at end of the period	$ 3,669