XML 132 R102.htm IDEA: XBRL DOCUMENT
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Shareholders' Equity - Summary of Nonvested Share Activity (Detail) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Employees [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 9,641,665us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards granted, Number of shares | 6,959,210us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards forfeited, Number of Shares | (133,563)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards cancelled on failed vesting conditions, Number of Shares | (1,990,218)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCancelledOnFailedVestingConditionsInPeriod / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards vested, Number of Shares | (3,238,820)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Ending Balance, Number of Shares | 11,238,274us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Employees [Member] | 2012 CEO Special Bonus [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 67,241us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_TwoThousandTwelveChiefExecutiveOfficerSpecialBonusMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards vested, Number of Shares | (33,621)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_PlanNameAxis = stm_TwoThousandTwelveChiefExecutiveOfficerSpecialBonusMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Ending Balance, Number of Shares | 33,620us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_TwoThousandTwelveChiefExecutiveOfficerSpecialBonusMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Employees [Member] | Employee Plan 2012 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 3,152,539us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards forfeited, Number of Shares | (32,978)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards vested, Number of Shares | (1,739,357)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Ending Balance, Number of Shares | 1,380,204us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Employees [Member] | 2013 CEO Special Bonus [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 42,565us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_TwoThousandThirteenChiefExecutiveOfficerSpecialBonusMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards vested, Number of Shares | (14,188)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_PlanNameAxis = stm_TwoThousandThirteenChiefExecutiveOfficerSpecialBonusMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Ending Balance, Number of Shares | 28,377us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_TwoThousandThirteenChiefExecutiveOfficerSpecialBonusMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Employees [Member] | Employee Plan 2013 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 6,379,320us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandThirteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards forfeited, Number of Shares | (65,080)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandThirteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards cancelled on failed vesting conditions, Number of Shares | (1,990,218)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsCancelledOnFailedVestingConditionsInPeriod / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandThirteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards vested, Number of Shares | (1,451,654)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandThirteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Ending Balance, Number of Shares | 2,872,368us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandThirteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Employees [Member] | Employee Plan 2014 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Awards granted, Number of shares | 6,959,210us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandFourteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Awards forfeited, Number of Shares | (35,505)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandFourteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Ending Balance, Number of Shares | 6,923,705us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = stm_EmployeePlanTwoThousandFourteenMember / us-gaap_TitleOfIndividualAxis = stm_EmployeesMember |  |
Supervisory Board [Member] | 2005 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 31,115us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandFiveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 34,115us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandFiveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2005 |  |
Exercised | (9,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandFiveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember | (3,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandFiveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 22,115us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandFiveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 34,115us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandFiveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Supervisory Board [Member] | 2006 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 30,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSixMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 33,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSixMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2006 |  |
Exercised | (9,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSixMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember | (3,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSixMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 21,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSixMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 33,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSixMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Supervisory Board [Member] | 2007 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 60,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 82,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2007 |  |
Exercised | (13,500)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember | (22,500)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 46,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 82,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandSevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Supervisory Board [Member] | 2008 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 75,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandEightMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 85,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandEightMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2008 |  |
Exercised | (15,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandEightMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember | (10,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandEightMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 60,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandEightMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 85,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandEightMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Supervisory Board [Member] | 2009 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 75,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandNineMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 95,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandNineMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2009 |  |
Exercised |  | (20,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandNineMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 75,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandNineMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 95,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandNineMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Supervisory Board [Member] | 2010 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 82,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 107,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2010 |  |
Exercised | (7,500)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember | (25,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 75,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 107,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Supervisory Board [Member] | 2011 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 117,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandElevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 142,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandElevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2011 |  |
Exercised | (20,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandElevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember | (25,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandElevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 97,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandElevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 142,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandElevenMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Supervisory Board [Member] | 2012 [Member] |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |
Beginning Balance, Number of Shares | 122,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 157,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Year of grant | 2012 |  |
Exercised | (20,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember | (35,000)stm_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsExercisableNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |
Ending Balance, Number of Shares | 102,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  | 157,500us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_AwardTypeAxis = stm_TwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember
Shares corresponding to exercised option not yet available for trade as of 31.12.2014 | 5,000stm_NonVestedSharesCorrespondingToExercisedOptionNotYetAvailableForTrade / us-gaap_AwardTypeAxis = stm_TwoThousandTwelveMember / us-gaap_TitleOfIndividualAxis = stm_SupervisoryBoardMember |  |

X
- Definition Non vested Shares Corresponding To Exercised Option Not Yet Available For Trade + References No definition available. + Details
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Balance Type: | na
Period Type: | instant

X
- Definition Share based compensation arrangement by share based payment award equity instruments other than options cancelled on failed vesting conditions in period. + References No definition available. + Details
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- Definition Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Exercisable Number + References No definition available. + Details
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- Definition Year O Grant Date Of Non vested Share + References No definition available. + Details
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X
- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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Balance Type: | na
Period Type: | duration

X
- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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Balance Type: | na
Period Type: | duration

X
- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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Balance Type: | na
Period Type: | duration

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