Rent and Tenant Receivables and Other Assets, Net (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Straight-line rent receivable, net	$ 266,195,000	$ 259,106,000
Accounts receivable, net	41,556,000	36,939,000
Deferred costs, net	7,208,000	17,515,000
Investment in direct financing leases, net	9,341,000	13,254,000
Investment in Cole REITs	7,552,000	7,844,000
Prepaid expenses	3,453,000	5,022,000
Leasehold improvements, property and equipment, net	4,809,000	9,754,000
Other assets, net	8,281,000	16,658,000
Total	348,395,000	366,092,000
Property and equipment disposed of	4,300,000
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	700,000	1,200,000	$ 1,200,000
Write off of leasehold	0	0	0
Accumulated amortization	2,800,000	5,900,000
Property and Equipment [Member]
Property, Plant and Equipment [Line Items]
Accumulated amortization	5,400,000	7,000,000.0
Depreciation expense	1,300,000	2,300,000	1,800,000
Line of Credit [Member]
Property, Plant and Equipment [Line Items]
Amortization expense	2,100,000	7,300,000	10,400,000
Debt write off	1,800,000	0	0
Accumulated amortization for deferred costs	49,800,000	47,600,000
Rent Receivables [Member]
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts		1,000,000.0
Accounts Receivable [Member]
Property, Plant and Equipment [Line Items]
Allowance for doubtful accounts		5,300,000
Maximum [Member]
Property, Plant and Equipment [Line Items]
Write off of depreciation	$ 100,000	$ 800,000	$ 600,000