Organization and Summary of Significant Accounting Policies - Additional Information 2 (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Shipping and handling costs	$ 5,429,000	$ 5,606,800	$ 9,836,500	$ 11,229,000
General and Administrative Expense | Former Chief Financial Officer
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Severance costs	287,200
Shipping and Handling Costs
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Shipping and handling costs	$ 538,400	$ 621,600	$ 1,159,800	$ 1,253,200