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Fair Value Measurement - Additional Information (Detail) - USD ($) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Jul. 31, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Assets fair value disclosure nonrecurring basis |  | $ 0 | $ 0 | $ 0
Assets measured at fair value nonrecurring basis, loss incurred |  | $ 0 | $ 0 | $ 0
Senior Notes |  |  |  |
Held-to-maturity investments, investment maturity date | 2016-07 | 2016-07 |  |

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- Definition Investment, Maturity, Month and Year + References No definition available. + Details
Name: | simo_InvestmentMaturityMonthAndYear
Namespace Prefix: | simo_
Data Type: | xbrli:gYearMonthItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of addition (reduction) to the amount at which an asset could be incurred (settled) in a current transaction between willing parties. + References No definition available. + Details
Name: | us-gaap_AssetsFairValueAdjustment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a nonrecurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. + References No definition available. + Details
Name: | us-gaap_AssetsFairValueDisclosureNonrecurring
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |