v2.4.1.9
INVESTMENT IN EQUITY METHOD INVESTEES (Narrative) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
May 31, 2014
Dec. 31, 2013
Apr. 30, 2013
Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]          
Investments in equity method investees $ 27,352us-gaap_EquityMethodInvestments   $ 17,843us-gaap_EquityMethodInvestments    
Beijing Actions [Member]          
Schedule of Equity Method Investments [Line Items]          
Ownership percentage 45.80%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_ActionsMicroelectronicsCoLtdMember
  45.80%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_ActionsMicroelectronicsCoLtdMember
   
Investments in equity method investees 3,332us-gaap_EquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_ActionsMicroelectronicsCoLtdMember
  2,856us-gaap_EquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_ActionsMicroelectronicsCoLtdMember
   
Nann Capital [Member]          
Schedule of Equity Method Investments [Line Items]          
Ownership percentage   40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_NannCapitalCorporationNannCapitalMember
  40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_NannCapitalCorporationNannCapitalMember
40.00%us-gaap_EquityMethodInvestmentOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_NannCapitalCorporationNannCapitalMember
Investments in equity method investees $ 24,020us-gaap_EquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_NannCapitalCorporationNannCapitalMember
$ 9,016us-gaap_EquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_NannCapitalCorporationNannCapitalMember
$ 14,987us-gaap_EquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_NannCapitalCorporationNannCapitalMember
$ 3,712us-gaap_EquityMethodInvestments
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= acts_NannCapitalCorporationNannCapitalMember