Noncontrolling Interests (Details) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2019 USD ($) shares	Dec. 31, 2018	Dec. 31, 2016 property entity
Noncontrolling interests
Conversion ratio		1
Number of properties acquired | property			2
Number of joint ventures controlling interest acquired | entity			2
Senior Unsecured Term Loans | $70 million senior unsecured term loan | Subsequent event
Noncontrolling interests
Repayments of long-term debt | $	$ 70.0
Tau Operating Partnership
Noncontrolling interests
Ownership interest (as a percent)		99.40%
Tau Operating Partnership | Subsequent event
Noncontrolling interests
Ownership interest (as a percent)	100.00%
Number of partnership units redeemed | shares	317,022
Realty Income, L.P.
Noncontrolling interests
Ownership interest (as a percent)		98.50%
Third-party partnership ownership interest (as a percent)		1.50%
Other Noncontrolling Interest Entity One
Noncontrolling interests
Ownership interest (as a percent)		94.971%
Other Noncontrolling Interest Entity Two
Noncontrolling interests
Ownership interest (as a percent)		100.00%