Number of days for notification of product defect

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Revenue Recognition, Number Of Days Before Revenue Is Recognized Due To Trial Period

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Significant Accounting Policies [Line Items]

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Warranty Term

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Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

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A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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Percentage of voting equity interests acquired at the acquisition date in the business combination.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Total loss recognized during the period from the impairment of goodwill plus the loss recognized in the period resulting from the impairment of the carrying amount of intangible assets, other than goodwill.

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No definition available.

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The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

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- Definition

The amount of estimated interest accrued as of the balance sheet date arising from income tax examinations.

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The sum of the amounts of estimated penalties and interest recognized in the period arising from income tax examinations.

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- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount of noncurrent assets classified as other.

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Amount of expense charged against earnings to allocate the cost of tangible and intangible assets over their remaining economic lives, classified as other.

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Amount of liabilities classified as other, due after one year or the normal operating cycle, if longer.

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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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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

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No definition available.

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Summary of Significant Accounting Policies (Narrative) (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Significant Accounting Policies [Line Items]
Number of reportable segments \| segment	2
Revenue recognized after shipment because the customer has the right to return the product during this trial period phase, in days	60 days
Number of days for notification of product defect	30 days
Warranty term	1 year
Allowance for doubtful accounts	$ 332,000	$ 170,000
Depreciation expense	1,739,000	1,870,000	$ 1,524,000
Impairment of long-lived assets from continuing operations	0
Impairment of goodwill or intangible assets	0	0	0
Other assets, net	3,835,000	1,557,000
Other long-term liabilities	3,172,000	707,000
Amortization expense	455,000	159,000	$ 231,000
Tax related interest accrued	0	0
Tax interest or penalties recognized	$ 0	$ 0
Maximum term	6 years	6 years	6 years
Advertising costs	$ 1,696,000	$ 190,000	$ 0
Research and development	4,458,000	4,688,000	4,279,000
NXP [Member]
Significant Accounting Policies [Line Items]
Other assets, net	2,732,000
Other long-term liabilities	$ 2,600,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Acquired finite-lived intangible assets amortization period	18 years
Minimum [Member] \| Building and Improvements [Member]
Significant Accounting Policies [Line Items]
Estimated useful life	5 years
Minimum [Member] \| Machinery and Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful life	3 years
Maximum [Member]
Significant Accounting Policies [Line Items]
Acquired finite-lived intangible assets amortization period	20 years
Vesting period of options under equity incentive plan	3 years
Maximum term	10 years
Maximum [Member] \| Building and Improvements [Member]
Significant Accounting Policies [Line Items]
Estimated useful life	40 years
Maximum [Member] \| Machinery and Equipment [Member]
Significant Accounting Policies [Line Items]
Estimated useful life	12 years
earVenture [Member]
Significant Accounting Policies [Line Items]
Ownership percentage	50.00%
Hearing Help Express (HHE) [Member]
Significant Accounting Policies [Line Items]
Ownership percentage	20.00%
Acquisition of remaining percentage stake	80.00%
Customer Funded Tooling [Member]
Significant Accounting Policies [Line Items]
Research and development	$ 95,000	$ 102,000	$ 121,000