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Revenue - Trade Sale Revenue (Detail) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Dec. 31, 2018
Revenue from Contract with Customer [Abstract]          
Trade sales receivable $ 1,818,542   $ 1,818,542   $ 1,606,283
Trade sales payable 1,312,993   1,312,993   $ 1,250,454
Trade sales revenue $ 2,005,613 $ 2,790,888 $ 6,513,855 $ 6,409,976