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Property And Equipment - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014
Operating Leased Assets [Line Items] |
Operating leased renewal period of land and buildings | 3 years
Annual lease and rental income | $ 41 simo_OperatingLeasesIncomeStatementAnnualRevenue
Land |
Operating Leased Assets [Line Items] |
Net carrying value lease asset | 603 simo_OperatingLeasedAssetsNet / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_LandMember
Buildings |
Operating Leased Assets [Line Items] |
Net carrying value lease asset | $ 161 simo_OperatingLeasedAssetsNet / us-gaap_PropertyPlantAndEquipmentByTypeAxis = us-gaap_BuildingMember

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- Definition Operating Leased Assets, Net + References No definition available. + Details
Name: | simo_OperatingLeasedAssetsNet
Namespace Prefix: | simo_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition Operating Lease Renewal Period + References No definition available. + Details
Name: | simo_OperatingLeaseRenewalPeriod
Namespace Prefix: | simo_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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- Definition Operating Leases, Income Statement, Annual Revenue + References No definition available. + Details
Name: | simo_OperatingLeasesIncomeStatementAnnualRevenue
Namespace Prefix: | simo_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
Name: | us-gaap_OperatingLeasedAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_LandMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |