Real Estate Investments and Related Intangibles - Property Acquisitions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) property land_parcel	Dec. 31, 2016 USD ($) property	Dec. 31, 2015 USD ($) property land_parcel
2017 Acquisitions [Member]
Business Acquisition [Line Items]
Number of properties acquired | property	88
Number of land parcels acquired | land_parcel	3
Total purchase price of assets acquired | $	$ 748,784
2016 Acquisitions [Member]
Business Acquisition [Line Items]
Number of properties acquired | property		8
Total purchase price of assets acquired | $		$ 100,194
2015, Acquisitions [Member]
Business Acquisition [Line Items]
Number of properties acquired | property			16
Number of land parcels acquired | land_parcel			9
Total purchase price of assets acquired | $			$ 36,319
Accounting Standards Update 2017-01 [Member] | New Accounting Pronouncement, Early Adoption, Effect [Member]
Business Acquisition [Line Items]
Capitalized acquisition costs | $	$ 3,300
Bob Evans [Member]
Business Acquisition [Line Items]
Number of real estate properties acquired | property	22