XML 98 R85.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Long-Term Debt - Long-Term Debt (Parenthetical) (Detail) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017
Debt Instrument [Line Items] |  |
Interest rate |  | 1.00%
3.57% due 2020, floating interest rate at Libor + 1.099% [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2020 |
Interest rate | 3.57% |
Description of floating rate basis | Libor + 1.099% |
Basis spread on floating rate | 1.099% |
3.69% due 2020, floating interest rate at Libor + 1.056% [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2020 |
Interest rate | 3.69% |
Description of floating rate basis | Libor + 1.056% |
Basis spread on floating rate | 1.056% |
0.50% due 2020, floating interest rate at Euribor + 0.817% [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2020 |
Interest rate | 0.50% |
Description of floating rate basis | Euribor + 0.817% |
Basis spread on floating rate | 0.817% |
3.30% due 2021, floating interest rate at Libor + 0.525% [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2021 |
Interest rate | 3.30% |
Description of floating rate basis | Libor + 0.525% |
Basis spread on floating rate | 0.525% |
3.46% due 2021, floating interest rate at Libor + 0.572% [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2021 |
Interest rate | 3.46% |
Description of floating rate basis | Libor + 0.572% |
Basis spread on floating rate | 0.572% |
0.32% due 2028, floating interest rate at Libor 0.589% [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2028 |
Interest rate | 0.32% |
Description of floating rate basis | Euribor + 0.589% |
Basis spread on floating rate | 0.589% |
Zero-coupon, due 2022 (Tranche A) [Member] | Senior Unsecured Convertible Bonds [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2022 |
Interest rate | 0.00% |
0.25%, due 2024 (Tranche B) [Member] |  |
Debt Instrument [Line Items] |  |
Interest rate | 0.25% |
0.25%, due 2024 (Tranche B) [Member] | Senior Unsecured Convertible Bonds [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2024 |
Interest rate | 0.25% |
0.31% (weighted average), due 2018-2023, fixed interest rate [Member] |  |
Debt Instrument [Line Items] |  |
Interest rate | 0.31% |
0.31% (weighted average), due 2018-2023, fixed interest rate [Member] | Minimum [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2018 |
0.31% (weighted average), due 2018-2023, fixed interest rate [Member] | Maximum [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2023 |
0.41% (weighted average), due 2018, fixed interest rate [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2018 |
Interest rate | 0.41% |
0.87% (weighted average), due 2020, fixed interest rate [Member] |  |
Debt Instrument [Line Items] |  |
Long-term debt maturity date | 2020 |
Interest rate | 0.87% |

X
- Definition Debt Instrument Maturity Year + References No definition available. + Details
Name: | stm_DebtInstrumentMaturityYear
Namespace Prefix: | stm_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_FundingProgramLoansDueTwoThousandAndTwentyFloatingInterestRateAtLiborSixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_FundingProgramLoansDueTwoThousandAndTwentyFloatingInterestRateAtLiborSevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_FundingProgramLoansDueTwoThousandAndTwentyFloatingInterestRateAtLiborEightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_FundingProgramLoansDueTwoThousandAndTwentyOneFloatingInterestRateAtLiborNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_FundingProgramLoansDueTwoThousandAndTwentyOneFloatingInterestRateAtLiborTenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_FundingProgramLoansDueTwoThousandAndTwentyEightFloatingInterestRateAtLiborElevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_ZeroCouponDueTwoThousandAndTwentyTwoTrancheaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=stm_SeniorUnsecuredConvertibleBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_ZeroPointTwoFivePercentageDueTwoThousandAndTwentyFourTranchebMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_ZeroPointThreeOnePercentageWeightedAverageDueTwoThousandAndEighteenToTwoThousandAndTwentyThreeFixedInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_ZeroPointFourOnePercentageWeightedAverageDueTwoThousandAndEighteenFixedInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=stm_ZeroPointEightSevenPercentageWeightedAverageDueTwoThousandAndTwentyFixedInterestRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |