Organization and Summary of Significant Accounting Policies - Additional Information 1 (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Significant financial instruments with off-balance sheet risk	$ 0		$ 0
Long-term debt	0		0		$ 1,200,000
Line-of-credit outstanding balance	0		0		$ 0
Interest and penalties recognized in consolidated statements of income			0
Accrued interest or penalties related to uncertain tax positions	0		$ 0
Effective income tax rate			24.80%	38.70%
U.S. Corporate income tax rate			21.00%		35.00%
Reserve for reduction in account receivable			$ 834,200		$ 1,069,700
Trade promotions to customers	$ 671,700	$ 712,100	$ 1,272,100	$ 1,331,800
Minimum
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			3 years
Useful lives of intangible assets			5 years
Minimum | Production Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			15 years
Minimum | Production Support Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			3 years
Minimum | Office Furniture and Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			10 years
Minimum | Office Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			3 years
Maximum
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			20 years
Useful lives of intangible assets			15 years
Maximum | Production Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			20 years
Maximum | Production Support Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			10 years
Maximum | Office Furniture and Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			20 years
Maximum | Office Equipment
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Useful life of property, plant and equipment			5 years