Discontinued Operations - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 13, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Provision (benefit) for income taxes	$ 6,882	$ 7,136	$ 4,589
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]
Consideration paid at closing				$ 120,000
Contingent consideration, payment period	6 years
Contingent consideration, maximum consideration receivable				$ 80,000
Provision (benefit) for income taxes	$ 13,839	$ (10,837)	$ (40,892)