Credit Facility Amount Outstanding

No definition available.

Name:	stm_CreditFacilityAmountOutstanding
Namespace Prefix:	stm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Debt instrument convertible conversion premium percentage.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Maturity Year

+ References

No definition available.

+ Details

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Namespace Prefix:	stm_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Line Of Credit Facility Amount Drawn

+ References

No definition available.

+ Details

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Namespace Prefix:	stm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Unamortized Debt Discount And Debt Issuance Costs

+ References

No definition available.

+ Details

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Namespace Prefix:	stm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Adjustment to additional paid in capital resulting from the recognition of convertible debt instruments as two separate components - a debt component and an equity component. This bifurcation may result in a basis difference associated with the liability component that represents a temporary difference for purposes of applying accounting for income taxes. The initial recognition of deferred taxes for the tax effect of that temporary difference is as an adjustment to additional paid in capital.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 25
-Paragraph 22
-URI http://asc.fasb.org/extlink&oid=51819886&loc=SL6014347-161799

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The value of the financial instrument(s) that the original debt is being converted into in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Dividend or interest rate associated with the financial instrument issued in exchange for the original debt being converted in a noncash or part noncash transaction. Noncash are transactions that affect recognized assets or liabilities but that do not result in cash receipts or cash payments. Part noncash refers to that portion of the transaction not resulting in cash receipts or cash payments.

+ References

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or payments in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6031898-161870

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Description of the frequency of periodic payments (monthly, quarterly, annual).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- 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

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from the issuance of long-term debt that is not secured by collateral. Excludes proceeds from tax exempt unsecured debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3255-108585

+ Details

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Balance Type:	debit
Period Type:	duration

- Details

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- Details

Name:	us-gaap_LineOfCreditFacilityAxis=stm_UncommittedShortTermCreditFacilitiesMember
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- Details

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- Details

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- Details

Name:	us-gaap_LongtermDebtTypeAxis=stm_SeniorUnsecuredConvertibleBondsMember
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- Details

Name:	us-gaap_DebtInstrumentAxis=stm_ZeroCouponDueTwoThousandNineteenTrancheAMember
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- Details

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- Details

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Long-Term Debt - Additional Information (Detail) $ / shares in Units, € in Millions			12 Months Ended
	Oct. 03, 2016 USD ($) shares	Jul. 03, 2014 USD ($) $ / shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2016 EUR (€)	Mar. 31, 2013 EUR (€)	Mar. 12, 2013 USD ($)
Debt Instrument [Line Items]
Net proceeds from issuance of senior unsecured convertible bonds					$ 994,000,000
Conversion price adjusted	1.24%
Conversion features of the instruments value			$ 121,000,000	$ 0	$ 121,000,000
Allocated debt issuance costs		$ 1,000,000
Unamortized debt discount and issuance costs totalled			74,000,000	$ 95,000,000
Medium Term Credit Facilities [Member]
Debt Instrument [Line Items]
Unutilized committed medium term credit facilities			558,000,000
Multi Currency Loan to Support our Industrial and R&D Programs [Member]
Debt Instrument [Line Items]
Line of credit outstanding amount \| €							€ 350
Amount outstanding			294,000,000
Line of credit amount withdrawn								$ 471,000,000
Fair Value, Inputs, Level 3 [Member]
Debt Instrument [Line Items]
Fair value of liability component		878,000,000
Europe [Member] \| Multi Currency Loan to Support our Industrial and R&D Programs [Member]
Debt Instrument [Line Items]
Line of credit outstanding amount \| €						€ 350
Amount outstanding			213,000,000
Line of credit amount withdrawn			$ 321,000,000			€ 100
Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Net proceeds from issuance of senior unsecured convertible bonds		$ 994,000,000
Zero Coupon due 2019 (Tranche A) [Member]
Debt Instrument [Line Items]
Interest rate			1.00%			1.00%
Senior unsecured convertible bonds conversion premium rate		30.00%
Debt discount rate			2.40%	2.40%
Zero Coupon due 2019 (Tranche A) [Member] \| Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Debt instrument principal amount		$ 600,000,000
Long-term debt maturity date			2019
Interest rate		0.00%	0.00%			0.00%
1.0% due 2021 (Tranche B) [Member]
Debt Instrument [Line Items]
Debt instrument periodic payment			Semi-annually
Interest rate			1.00%			1.00%
Senior unsecured convertible bonds conversion premium rate		31.00%
Debt discount rate			3.22%	3.22%
1.0% due 2021 (Tranche B) [Member] \| Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Debt instrument principal amount		$ 400,000,000
Long-term debt maturity date			2021
Interest rate		1.00%	1.00%			1.00%
Dual Tranche Senior Unsecured Convertible Bonds [Member] \| Senior Unsecured Convertible Bonds [Member]
Debt Instrument [Line Items]
Debt instrument principal amount		$ 1,000,000,000
Senior unsecured convertible bonds conversion price \| $ / shares		$ 12
Tranche One [Member]
Debt Instrument [Line Items]
Debt conversion, converted instrument, shares issued (in shares) \| shares	16,491
Debt conversion, bond par value	$ 200,000
Tranche Two [Member]
Debt Instrument [Line Items]
Debt conversion, converted instrument, shares issued (in shares) \| shares	16,366
Debt conversion, bond par value	$ 994,000,000