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Summary of Significant Accounting Policies - Contract with Customer, Asset and Liability (Details)
6 Months Ended
Jun. 30, 2018
USD ($)
Accounting Policies [Abstract]  
Balance at December 31, 2017 $ 378,896,803
Cumulative effect of accounting change (1,780,050)
Billings in advance of revenue recognition 186,526
Revenue recognized (740,281)
Balance at March 31, 2018 $ 376,562,998