Consolidated Statements of Cash Flows (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income (loss)	$ 129us-gaap_ProfitLoss	$ (629)us-gaap_ProfitLoss	$ (2,188)us-gaap_ProfitLoss
Items to reconcile net income (loss) and cash flows from operating activities:
Depreciation and amortization	811us-gaap_DepreciationAndAmortization	910us-gaap_DepreciationAndAmortization	1,107us-gaap_DepreciationAndAmortization
Interest and amortization of issuance costs on convertible bonds	10us-gaap_AmortizationOfFinancingCosts
(Gain) loss on financial instruments, net	1stm_GainLossOnFinancialInstrumentsNet		(3)stm_GainLossOnFinancialInstrumentsNet
Gain on sale of businesses	(22)us-gaap_GainLossOnSaleOfBusiness	(80)us-gaap_GainLossOnSaleOfBusiness
Non-cash stock-based compensation	36us-gaap_ShareBasedCompensation	26us-gaap_ShareBasedCompensation	11us-gaap_ShareBasedCompensation
Other non-cash items	(78)us-gaap_OtherNoncashIncomeExpense	(113)us-gaap_OtherNoncashIncomeExpense	(65)us-gaap_OtherNoncashIncomeExpense
Deferred income tax	(143)us-gaap_DeferredIncomeTaxExpenseBenefit	(48)us-gaap_DeferredIncomeTaxExpenseBenefit	(80)us-gaap_DeferredIncomeTaxExpenseBenefit
(Income) loss on equity-method investments	43	122	24
Impairment, restructuring charges and other related closure costs, net of cash payments	4	145	1,303
Changes in assets and liabilities:
Trade receivables, net	119us-gaap_IncreaseDecreaseInReceivables	(57)us-gaap_IncreaseDecreaseInReceivables	35us-gaap_IncreaseDecreaseInReceivables
Inventories		(22)us-gaap_IncreaseDecreaseInInventories	191us-gaap_IncreaseDecreaseInInventories
Trade payables	(70)	(139)	148
Other assets and liabilities, net	(125)	251	129
Net cash from operating activities	715	366	612
Cash flows from investing activities:
Payment for purchase of tangible assets	(505)	(543)	(492)
Proceeds from sale of tangible assets	9	12	16
Payment for purchase of marketable securities	(333)		(450)
Proceeds from sale of marketable securities	58	184	630
Release of restricted cash		3	3
Net cash variation for joint ventures deconsolidation	9	(21)
Partial asset distribution from joint ventures in liquidation	15
Payment for funding of joint ventures liquidation		(15)
Payment for purchase of intangible assets	(58)	(78)	(56)
Payment for purchase of financial assets	(9)us-gaap_PaymentsToAcquireInvestments	(14)us-gaap_PaymentsToAcquireInvestments	(61)us-gaap_PaymentsToAcquireInvestments
Proceeds from sale of financial assets	1	1	15
Proceeds received in sale of businesses	29	92
Payment for business acquisitions, net of cash and cash equivalents acquired			(1)
Net cash used in investing activities	(784)	(379)	(396)
Cash flows from financing activities:
Proceeds from long-term debt	3	477	464
Proceeds from short-term borrowings		145us-gaap_ProceedsFromShortTermDebt	390us-gaap_ProceedsFromShortTermDebt
Net proceeds from issuance of senior unsecured convertible bonds	994
Repurchase / repayment of issued debt		(455)stm_RepurchaseOfIssuedDebt	(219)stm_RepurchaseOfIssuedDebt
Repayment of long-term debt	(223)us-gaap_RepaymentsOfLongTermDebt	(166)us-gaap_RepaymentsOfLongTermDebt	(109)us-gaap_RepaymentsOfLongTermDebt
Repayment of short-term borrowings		(35)us-gaap_RepaymentsOfShortTermDebt	(20)us-gaap_RepaymentsOfShortTermDebt
Decrease in short-term facilities			(7)
Capital increase	1
Repurchase of common stock	(156)
Dividends paid to stockholders	(354)us-gaap_PaymentsOfDividendsCommonStock	(346)us-gaap_PaymentsOfDividendsCommonStock	(355)us-gaap_PaymentsOfDividendsCommonStock
Dividends paid to noncontrolling interests	(3)	(4)	(5)
Other financing activities		(4)	(4)
Net cash from (used in) financing activities	262	(388)	135
Effect of changes in exchange rates	(12)	(13)	(13)
Net cash increase (decrease)	181	(414)	338
Cash and cash equivalents at beginning of the period	1,836	2,250	1,912
Cash and cash equivalents at end of the period	2,017	1,836	2,250
Supplemental cash information:
Interest paid	11us-gaap_InterestPaid	10us-gaap_InterestPaid	26us-gaap_InterestPaid
Income tax paid	$ 30us-gaap_IncomeTaxesPaid	$ 23us-gaap_IncomeTaxesPaid	$ 51us-gaap_IncomeTaxesPaid

This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain or loss of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain or loss which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains or losses realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments of the subject investments. Finally, this item would also include aggregate net gain and losses (whether realized or unrealized) on all derivative instruments held for trading purposes whether or not settled physically.

No definition available.