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Number of largest customer.

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Payment period.

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Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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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 before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation.

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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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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets.

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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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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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Summary of Significant Accounting Policies and Basis of Presentation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Customer	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Accounting Policies [Line Items]
Cash and cash equivalents	$ 177,187,000	$ 144,479,000	$ 85,700,000	$ 54,885,000
Depreciation expense	24,873,000	18,399,000	17,528,000
Impairment of goodwill	0	0	0
Share based compensation expense	8,147,000	12,316,000	8,601,000
Related deferred tax benefit	4,508,000	3,129,000
Stock options outstanding under the 1993,1997, 2006 and 2011 Stock Option Plans
Accounting Policies [Line Items]
Related deferred tax benefit	2,891,000	3,787,000	2,949,000
Production tooling
Accounting Policies [Line Items]
Reimbursable tooling capitalized within prepaid expenses and other current assets	$ 5,604,000	5,174,000
Minimum
Accounting Policies [Line Items]
Payment terms of contracts	30 days
Minimum \| Production tooling
Accounting Policies [Line Items]
Property plant and equipment, estimated useful life	2 years
Maximum
Accounting Policies [Line Items]
Payment terms of contracts	120 days
Maximum \| Production tooling
Accounting Policies [Line Items]
Property plant and equipment, estimated useful life	7 years
Patents
Accounting Policies [Line Items]
Amortization of intangibles	$ 12,675,000	$ 12,751,000	$ 16,941,000
Concentration of Credit Risk \| Accounts receivable \| Lear Corporation
Accounting Policies [Line Items]
Concentration risk percentage	25.00%	28.00%
Concentration of Credit Risk \| Accounts receivable \| Adient
Accounting Policies [Line Items]
Concentration risk percentage	24.00%	27.00%
Concentration of Credit Risk \| Accounts receivable \| Faurecia
Accounting Policies [Line Items]
Concentration risk percentage	7.00%	5.00%
Customer Concentration Risk \| Sales Revenue
Accounting Policies [Line Items]
Number of largest customer \| Customer	3
Customer Concentration Risk \| Sales Revenue \| Lear Corporation
Accounting Policies [Line Items]
Concentration risk percentage	21.00%	22.00%	21.00%
Revenues from sales	$ 192,425,000
Customer Concentration Risk \| Sales Revenue \| Adient
Accounting Policies [Line Items]
Concentration risk percentage	21.00%	23.00%	24.00%
Revenues from sales	$ 192,831,000
Customer Concentration Risk \| Sales Revenue \| Bosch
Accounting Policies [Line Items]
Concentration risk percentage	8.00%	9.00%	9.00%
Revenues from sales	$ 74,092,000
Foreign Jurisdictions
Accounting Policies [Line Items]
Cash and cash equivalents	$ 162,881,000	$ 140,088,000