XML 19 R55.htm IDEA: XBRL DOCUMENT v2.4.1.9
Goodwill And Acquired Intangible Assets - Additional Information (Detail) (USD $)
 12 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2007
Oct. 30, 2011
Goodwill and Intangible Assets Disclosure [Line Items]          
Amortization of intangible assets $ 0us-gaap_AmortizationOfIntangibleAssets $ 0us-gaap_AmortizationOfIntangibleAssets $ 0us-gaap_AmortizationOfIntangibleAssets    
Intangible asset impairment losses 0us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill 0us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill 0us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill    
Goodwill impairment 0us-gaap_GoodwillImpairmentLoss 0us-gaap_GoodwillImpairmentLoss 0us-gaap_GoodwillImpairmentLoss    
Goodwill 35,467,000us-gaap_Goodwill 35,474,000us-gaap_Goodwill      
FCI and Centronix          
Goodwill and Intangible Assets Disclosure [Line Items]          
Goodwill acquired during period       66,300,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_BusinessAcquisitionAxis
= simo_AcquiredEntitiesMember		  
BusinessAcquisitionOne          
Goodwill and Intangible Assets Disclosure [Line Items]          
Goodwill acquired during period         $ 156,000us-gaap_GoodwillAcquiredDuringPeriod
/ us-gaap_BusinessAcquisitionAxis
= simo_BusinessAcquisitionOneMember