Quarterly report pursuant to Section 13 or 15(d)

Nature of Business and Summary of Significant Accounting Policies, Accounts Receivable and Allowance for Doubtful Accounts (Details)

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Nature of Business and Summary of Significant Accounting Policies, Accounts Receivable and Allowance for Doubtful Accounts (Details) - USD ($)
$ in Millions
Sep. 30, 2019
Dec. 31, 2018
Accounts Receivable and Allowance for Doubtful Accounts [Abstract]    
Allowance for doubtful accounts $ 0 $ 0