Related Party Transactions and Arrangements (Fees and Participations Paid in Connection With the Operations of the Company, Incurred, Waived and Payable) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Related Party Transaction [Line Items]
Expenses incurred	$ 2,683	$ 3,353
Payable (Receivable)	158		$ 529
Acquisition fees and related cost reimbursements | Acquisition fees and reimbursements:
Related Party Transaction [Line Items]
Expenses incurred	0	0
Payable (Receivable)	0		0
Financing coordination fees | Acquisition fees and reimbursements:
Related Party Transaction [Line Items]
Expenses incurred	0	1,050
Payable (Receivable)	0		0
Operating fees incurred from related parties | Ongoing fees:
Related Party Transaction [Line Items]
Expenses incurred	1,483	1,538
Payable (Receivable)	(46)		(18)
Professional fees and other reimbursements | Ongoing fees:
Related Party Transaction [Line Items]
Expenses incurred	1,161	706
Payable (Receivable)	204		527
Distributions on Class B units | Ongoing fees:
Related Party Transaction [Line Items]
Expenses incurred	39	$ 59
Payable (Receivable)	$ 0		$ 20