Commitments and Contingencies - Agreements (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Business Acquisition, Contingent Consideration [Line Items]
Other expenses	$ 1,250,000	$ 318,000	$ 1,444,000	$ 578,000
Letters of credit outstanding	5,600,000		$ 5,600,000
Minimum | Property Acquisition under Agreement with Columbus Nova | Incentive Fee | Fair Value, Inputs, Level 3 | Market And Income Approach Valuation Technique | Contingent Consideration
Business Acquisition, Contingent Consideration [Line Items]
Fair Value Inputs, Cap Rate			6.50%
Fair Value Inputs, Discount Rate					8.00%
Fair Value Inputs Exit Capitalization Rate					7.00%
Maximum | Property Acquisition under Agreement with Columbus Nova | Incentive Fee | Fair Value, Inputs, Level 3 | Market And Income Approach Valuation Technique | Contingent Consideration
Business Acquisition, Contingent Consideration [Line Items]
Fair Value Inputs, Cap Rate			9.25%
Fair Value Inputs, Discount Rate					12.00%
Fair Value Inputs Exit Capitalization Rate					12.00%
Other Expense [Member] | Property Acquisition under Agreement with Columbus Nova
Business Acquisition, Contingent Consideration [Line Items]
Other expenses	900,000	$ 0	$ 900,000	$ 0
Accounts Payable and Accrued Liabilities [Member] | Property Acquisition under Agreement with Columbus Nova
Business Acquisition, Contingent Consideration [Line Items]
Other Liabilities	$ 900,000		$ 900,000		$ 0