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Financial Instruments - Additional Information (Detail) (USD $)
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3 Months Ended | |
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Mar. 31, 2013
debt_security
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Dec. 31, 2012
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| Debt Instrument [Line Items] | ||
| Number of corporate debt securities | 16 | |
| Fair value of debt | $ 24,900,000 | |
| Gross unrealized losses | 16,000 | 4,000 |
| Transfer of securities, Level 1 | 0 | |
| Transfer of securities, Level 2 | 0 | |
| Transfer of securities, Level 3 | $ 0 | |
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Minimum [Member]
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| Debt Instrument [Line Items] | ||
| Due date of company's long term available for sale securities | 1 year | |
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Maximum [Member]
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| Debt Instrument [Line Items] | ||
| Period of unrealized loss position | 12 months | |
| Due date of company's long term available for sale securities | 2 years |
| X | ||||||||||
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- Definition
Available for sale securities noncurrent maturity period. No definition available.
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| X | ||||||||||
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- Definition
Period of unrealized loss position. No definition available.
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| X | ||||||||||
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- Definition
This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
This item represents the gross unrealized losses for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities. No definition available.
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| X | ||||||||||
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- Definition
Disclosure regarding factors used to determine that the impairment of securities not categorized as either held-to-maturity securities or trading securities (hence equal to available for sale securities) where cost exceeds fair value is not an other than temporary impairment (OTTI). This item contains disclosure of the number of investment positions in the available-for-sale investments determined to be temporarily impaired. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Amount of transfers of assets measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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