Related Party Transactions and Arrangements - Schedule of Revenue (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Related-party revenues	$ 8,002	$ 106,721	$ 118,418
Affiliated Entity [Member] | Revolving Credit Facility [Member] | Credit Facility [Member]
Related Party Transaction [Line Items]
Interest income on Affiliate Lines of Credit	28	262	453
Offering-related fees and reimbursements [Member]
Related Party Transaction [Line Items]
Related-party revenues	1,027	16,096	36,526
Selling commissions [Member]
Related Party Transaction [Line Items]
Related-party revenues	407	7,746	19,943
Dealer manager and distribution fees [Member]
Related Party Transaction [Line Items]
Related-party revenues	431	5,021	8,300
Reimbursement revenue [Member]
Related Party Transaction [Line Items]
Related-party revenues	189	3,329	8,283
Transaction service fees and reimbursements [Member]
Related Party Transaction [Line Items]
Related-party revenues	334	13,929	12,533
Acquisition fees [Member]
Related Party Transaction [Line Items]
Related-party revenues	119	11,049	9,513
Financing coordination fee [Member]
Related Party Transaction [Line Items]
Related-party revenues	0	100	220
Reimbursement revenues [Member]
Related Party Transaction [Line Items]
Related-party revenues	215	2,780	2,800
Management fees and reimbursements [Member]
Related Party Transaction [Line Items]
Related-party revenues	6,613	76,434	68,906
Asset and property management fees and leasing fees [Member]
Related Party Transaction [Line Items]
Related-party revenues	161	220	220
Advisory and performance fee revenue [Member]
Related Party Transaction [Line Items]
Related-party revenues	5,023	57,765	51,099
Reimbursement revenues [Member]
Related Party Transaction [Line Items]
Related-party revenues	$ 1,429	$ 18,449	$ 17,587
Selling commissions allowable [Member] | Cole REITs [Member]
Related Party Transaction [Line Items]
Selling commissions reallowed	100.00%	100.00%	100.00%
Dealer manager fees reimbursement [Member]
Related Party Transaction [Line Items]
Related-party revenues	$ 200	$ 2,100	$ 3,200