Organization and Summary of Significant Accounting Policies - Additional Information 1 (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule Of Organization And Presentation Of Financial Statements [Line Items]
Significant financial instruments with off-balance sheet risk	$ 0
Long-term debt	1,000,000		$ 1,200,000
Line-of-credit outstanding balance	0		$ 0
Interest and penalties recognized in consolidated statements of income	0
Accrued interest or penalties related to uncertain tax positions	$ 0
Effective income tax rate	26.10%	39.90%
U.S. Corporate income tax rate	21.00%		35.00%
Reserve for reduction in account receivable	$ 936,500		$ 1,069,700
Trade promotions to customers	$ 600,400	$ 619,700
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