Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Contract Liabilities (Details)

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Summary of Significant Accounting Policies - Contract Liabilities (Details) - USD ($)
9 Months Ended
Sep. 30, 2019
Dec. 31, 2018
Contract with Customer, Liability [Abstract]    
Amounts included in contract liability at the beginning of the period $ 2,686,000  
Deferred Revenue    
Contract with Customer, Liability [Abstract]    
Deferred Revenue   $ 2,686,000