Real Estate Investments - Assets Held for Sale (Details) $ in Thousands	1 Months Ended
	Sep. 30, 2020 USD ($) property	Dec. 31, 2019 USD ($) property
Long Lived Assets Held-for-sale [Line Items]
Number of properties reclassified to held for sale | property	4
Expected purchase price	$ 23,000
Net investment in property held for sale	$ 18,100
Number of properties held for sale | property	4	0
Balance Sheet Related Disclosures [Abstract]
Land	$ 330,840	$ 289,751
Building, improvements and lease intangibles	4,014,740	3,986,326
Personal property	10,962	10,538
Total real estate properties	4,381,189	4,359,993
Accumulated depreciation	(1,198,444)	(1,121,102)
Total real estate properties, net	3,182,745	3,238,891
Assets held for sale, net	20,051	37
Liabilities of assets held for sale	548	145
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Balance Sheet Related Disclosures [Abstract]
Land	1,664	0
Building, improvements and lease intangibles	26,871	0
Personal property	39	0
Total real estate properties	28,574	0
Accumulated depreciation	(10,443)	0
Total real estate properties, net	18,131	0
Other assets, net	1,920	37
Assets held for sale, net	20,051	37
Accounts payable and accrued liabilities	437	37
Other liabilities	111	108
Liabilities of assets held for sale	$ 548	$ 145