Summary of Significant Accounting Policies - Schedule of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Jun. 30, 2017
Dec. 31, 2016
Restricted Cash and Cash Equivalents Items [Line Items]        
Cash and cash equivalents $ 9,289 $ 8,798 $ 11,246  
Total cash, cash equivalents and restricted cash 27,658 114,707 63,523 $ 36,900
Collateral deposits        
Restricted Cash and Cash Equivalents Items [Line Items]        
Restricted cash 372 1,751 1,587  
Tenant improvements, repairs, and leasing commissions        
Restricted Cash and Cash Equivalents Items [Line Items]        
Restricted cash 9,147 8,257 10,392  
Master Trust Release        
Restricted Cash and Cash Equivalents Items [Line Items]        
Restricted cash 7,412 85,703 34,045  
Liquidity reserve        
Restricted Cash and Cash Equivalents Items [Line Items]        
Restricted cash 0 5,503 0  
Other        
Restricted Cash and Cash Equivalents Items [Line Items]        
Restricted cash $ 1,438 $ 4,695 $ 6,253