Supplemental Disclosures of Cash Flow Information (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) shares	Mar. 31, 2017 USD ($) building	Mar. 30, 2018 shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 27, 2013 shares
Supplemental Disclosures of Cash Flow Information
Cash paid for interest	$ 71,900,000	$ 75,600,000
Cash paid for income taxes	403,000	$ 2,500,000
Non-cash activities
Number of buildings damaged | building		2
Damaged buildings insurance receivables		$ 10,600,000
Reconciliation of cash and cash equivalents
Cash and cash equivalents shown in the consolidated balance sheets	20,627,000	27,598,000		$ 6,898,000
Impounds related to mortgages payable	5,923,000	2,074,000		4,565,000
Restricted escrow deposits	32,000	25,327,000		679,000
Total cash, cash equivalents, and restricted cash shown in the consolidated statements of cash flows	26,582,000	54,999,000		$ 12,142,000	$ 15,681,000
Properties under development
Supplemental Disclosures of Cash Flow Information
Interest capitalized to properties under development	$ 57,000	$ 190,000
Realty Income, L.P.
Non-cash activities
Number of partnership units issued | shares	242,007		242,007			534,546
Value of partnership units issued	$ 12,100,000