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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Sum of the carrying amounts as of the balance sheet date of deferred costs capitalized at the end of the reporting period that are expected to be charged against earnings within one year or the normal operating cycle, if longer.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 01, 2017
Foreign Currency Transaction Gain (Loss), before Tax	$ 65,000	$ 608,000	$ 80,000
Available-for-sale Securities	185,831,000	182,107,000
Stock Rotation Reserve	1,937,000	2,372,000
Goodwill, Impairment Loss	0	0	$ 0
Subsequent Event [Member] \| Accounting Standards Update 2016-09 [Member] \| Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption				$ 5,100,000
Distributors with Price Adjustment Rights [Member]
Deferred Revenue	3,700,000	2,800,000
Deferred Costs, Current	$ 300,000	$ 200,000
Sales Revenue, Goods, Net [Member] \| Customer Concentration Risk [Member] \| Distributor Sales [Member]
Concentration Risk, Percentage	88.00%	88.00%	89.00%
Land Use Rights [Member]
Finite-Lived Intangible Asset, Useful Life	50 years
Patents [Member]
Finite-Lived Intangible Asset, Useful Life	5 years
Minimum [Member]
Extended Product Warranty Term	1 year
Minimum [Member] \| Know-How And Developed Technologies [Member]
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum [Member]
Extended Product Warranty Term	2 years
Maximum [Member] \| Know-How And Developed Technologies [Member]
Finite-Lived Intangible Asset, Useful Life	5 years
Building and Building Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life	30 years
Building and Building Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life	40 years
Computer Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Computer Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life	7 years
Transportation Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life	5 years
Transportation Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life	15 years
Furniture and Fixtures [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life	5 years
Auction Rate Securities [Member]
Available-for-sale Securities	$ 5,400,000	$ 5,400,000
Interest and Other Income [Member]
Foreign Currency Transaction Gain (Loss), before Tax	$ 100,000	$ 600,000	$ 100,000