Noncontrolling Interests - Narrative (Details) $ in Thousands	1 Months Ended			12 Months Ended
	Dec. 31, 2019 property	Jan. 31, 2019 USD ($) shares	Dec. 31, 2018 entity	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2016 mortgage entity
Noncontrolling interests
Redemption of partnership units				$ 0	$ 21,123	$ 2,752
Conversion ratio				1
Number of properties acquired by acquiring a controlling interest	9						2
Number of joint ventures controlling interest acquired | entity							2
Number of entities in which all outstanding minority interests were acquired | entity			1
Term loans | $70 million senior unsecured term loan
Noncontrolling interests
Repayments of long-term debt		$ 70,000
Tau Operating Partnership units
Noncontrolling interests
Number of partnership units redeemed (in units) | shares		317,022
Redemption of partnership units		$ 20,200
Excess of redemption of units over carrying value as reduction to common stock and paid in capital		$ 6,900
Third-party partnership ownership interest (as a percent)		0.11%
Ownership interest (as a percent)		100.00%
Realty Income, L.P. units
Noncontrolling interests
Third-party partnership ownership interest (as a percent)				1.90%
Ownership interest (as a percent)				98.10%
Joint venture related to 2020 development property
Noncontrolling interests
Ownership interest (as a percent)	75.80%				75.80%
Joint venture related to 2019 property acquisitions
Noncontrolling interests
Ownership interest (as a percent)	89.90%				89.90%