Supplemental Disclosures of Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 30, 2018	Mar. 30, 2018	Dec. 31, 2015	Jun. 27, 2013
Supplemental Disclosures of Cash Flow Information
Cash paid for interest		$ 251,500	$ 240,400	$ 214,300
Cash paid for income taxes		4,700	3,800	3,600
Non-cash activities
Non-refundable escrow deposits for pending acquisitions	$ 200	200	7,500
Notes issued for acquisition of a portfolio of properties			125,900
Mortgage loans assumed				44,100
Net premiums recorded on mortgages assumed				692
Contributions by noncontrolling interests		18,848	0	15,906
Accrued costs on properties under development	5,500
Reconciliation of cash and cash equivalents
Cash and cash equivalents shown in the consolidated balance sheets	10,387	10,387	6,898
Impounds related to mortgages payable	9,555	9,555	4,565
Restricted escrow deposits	1,129	1,129	679
Total cash, cash equivalents, and restricted cash	$ 21,071	21,071	12,142	15,681			$ 50,333
Properties under development
Supplemental Disclosures of Cash Flow Information
Interest capitalized to properties under development		$ 369	$ 461	$ 469
Realty Income, L.P.
Non-cash activities
Number of partnership units issued	373,797	373,797			131,790	242,007		534,546
Value of partnership units issued	$ 18,800	$ 18,800