Discontinued Operations - Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income from discontinued operations	$ 3,501	$ 2,855
Cole Capital [Member] | Held-for-sale of Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Offering-related fees and reimbursements	1,027	4,316
Transaction service fees and reimbursements	334	4,006
Management fees and reimbursements	6,452	18,391
Total revenues	7,813	26,713
Cole Capital reallowed fees and commissions	602	2,660
Transaction costs	(654)	0
General and administrative	4,450	15,917
Amortization of intangible assets	0	4,140
Total operating expenses	4,398	22,717
Operating income	3,415	3,996
Other income (expense), net	0	5
Loss on disposition	(2,009)	0	$ (20,000)
Income before taxes	1,406	4,001
Benefit from (provision for) income taxes	2,095	(1,146)
Income from discontinued operations	$ 3,501	$ 2,855