Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Details)

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Stockholders' Equity (Details) - USD ($)
 1 Months Ended 6 Months Ended
Mar. 02, 2016
Jun. 30, 2016
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Preferred Stock, Shares Authorized   10,000,000 10,000,000   10,000,000
Preferred Stock, Par or Stated Value Per Share   $ 0.001 $ 0.001   $ 0.001
Common Stock, Shares Authorized   500,000,000 500,000,000   500,000,000
Common Stock, Par or Stated Value Per Share   $ 0.001 $ 0.001   $ 0.001
Common Stock, Shares, Outstanding   1,426,656 1,426,656   250,000
Common Stock, Dividends, Per Share, Cash Paid     $ 0.0852    
Dividends, Common Stock, Total     $ 285,703 $ 127,800  
Stock Issued During Period, Shares, New Issues   15,000,000      
Payments of Stock Issuance Costs   $ 1,369,565 $ 358,365 $ 0  
Noninterest Expense Offering Cost   $ 1,581,259      
Beneficial Ownership description   Our charter provides that, subject to certain exceptions, no person may beneficially or constructively own more than 9.8%, in value or in number of shares, whichever is more restrictive, of the outstanding shares of any class or series of our capital stock. On June 27, 2016, our board of directors approved a waiver of the 9.8% ownership limit in our charter allowing ZH USA, LLC to own up to 16.9% of our outstanding shares of common stock.      
IPO [Member]          
Stock Issued During Period, Shares, New Issues   13,043,479      
Shares Issued, Price Per Share   $ 10.00 $ 10.00    
Stock Issued During Period, Value, New Issues   $ 130,434,790 $ 130,434,790    
Payments of Stock Issuance Costs   9,661,160      
Proceeds from Issuance Initial Public Offering   $ 120,773,630      
Over-Allotment Option [Member]          
Stock Issued During Period, Shares, New Issues   1,956,521      
Shares Issued, Price Per Share   $ 10.00 $ 10.00    
Stock Issued During Period, Value, New Issues   $ 19,565,210      
Payments of Stock Issuance Costs   1,369,565      
Proceeds from Issuance Initial Public Offering   18,195,645      
Noninterest Expense Offering Cost   $ 1,581,259      
ZH USA, LLC [Member]          
Debt Conversion, Original Debt, Amount $ 15,000,000        
Debt Conversion, Converted Instrument, Shares Issued 1,176,656