Commitments - Company's Commitments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014
Recorded Unconditional Purchase Obligation [Line Items]
Operating leases, Total	$ 199
Operating leases, 2015	47
Operating leases, 2016	34
Operating leases, 2017	27
Operating leases, 2018	21
Operating leases, 2019	13
Operating leases, Thereafter	57
Purchase obligations, Total	391
Purchase obligations, 2015	362
Purchase obligations, 2016	15
Purchase obligations, 2017	6
Purchase obligations, 2018	5
Purchase obligations, 2019	3
Purchase obligations, Thereafter	0
Other obligations, Total	512stm_OtherObligation
Other obligations, 2015	284stm_OtherObligationDueCurrent
Other obligations, 2016	117stm_OtherObligationDueInTwoYears
Other obligations, 2017	81stm_OtherObligationDueInThreeYears
Other obligations, 2018	28stm_OtherObligationDueInFourYears
Other obligations, 2019	2stm_OtherObligationDueInFiveYears
Other obligations, Thereafter	0stm_OtherObligationDueThereafter
Company's commitments, Total	1,102stm_Obligation
Company's commitments, 2015	693stm_ObligationDueCurrent
Company's commitments, 2016	166stm_ObligationDueInTwoYears
Company's commitments, 2017	114stm_ObligationDueInThreeYears
Company's commitments, 2018	54stm_ObligationDueInFourYears
Company's commitments, 2019	18stm_ObligationDueInFiveYears
Company's commitments, Thereafter	57stm_ObligationDueThereafter
Equipment Purchase [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations, Total	171
Purchase obligations, 2015	171
Purchase obligations, Thereafter	0
Foundry Purchase [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations, Total	83
Purchase obligations, 2015	83
Purchase obligations, Thereafter	0
Software, Design, Technologies and Licenses [Member]
Recorded Unconditional Purchase Obligation [Line Items]
Purchase obligations, Total	137
Purchase obligations, 2015	108
Purchase obligations, 2016	15
Purchase obligations, 2017	6
Purchase obligations, 2018	5
Purchase obligations, 2019	3
Purchase obligations, Thereafter	$ 0

Obligation.

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Obligation Due Current.

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Obligation Due In Five Years.

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Obligation Due In Four Years.

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Obligation Due In Three Years.

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Obligation Due In Two Years.

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Obligation Due Thereafter.

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- Definition

Other Obligation.

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Other Obligation Due, Current.

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Other Obligation Due in Five Years.

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Other Obligation Due in Four Years.

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Other Obligation Due In Three Years.

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- Definition

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (a)

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 55

-Paragraph 40

-Subparagraph (Note 3)

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the recorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25383-109308

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Amount of the recorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the recorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the recorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the recorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the recorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Amount of the recorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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