Other Investments - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Variable Interest Entity [Line Items]
Ownership interest in investment	27.00%		27.00%
Purchase of components under agreement	$ 831,000	$ 1,210,000
Allocation of equity method income (loss)	0	0
Great Wall Semiconductor Corporation (GWS) [Member]
Variable Interest Entity [Line Items]
Investment in non-voting convertible preferred stock	0		0
Great Wall Semiconductor Corporation (GWS) [Member] \| Convertible Preferred Stock [Member]
Variable Interest Entity [Line Items]
Investment in non-voting convertible preferred stock	$ 5,000,000		$ 5,000,000

The amount of income (loss) from operations derived by the reporting entity during the period from the Variable Interest Entity (VIE).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph d

-URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5747-111685

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- Definition

The amount of purchases between the reporting entity and the Variable Interest Entity (VIE).

+ References

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- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5747-111685

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- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 5A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=28200181&loc=SL6759159-111685

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