Goodwill and acquisition-related intangibles - Acquisition-related intangibles (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Acquired Finite Lived Intangible Assets [Line Items]
Acquisition-related intangibles, gross carrying amount	$ 2,945		$ 2,948
Acquisition-related intangibles, accumulated amortization	1,123		1,046
Acquisition-related intangibles, net	1,822us-gaap_FiniteLivedIntangibleAssetsNet		1,902us-gaap_FiniteLivedIntangibleAssetsNet
Amortization of acquisition-related intangibles	80us-gaap_AmortizationOfIntangibleAssets	81us-gaap_AmortizationOfIntangibleAssets
Developed technology
Acquired Finite Lived Intangible Assets [Line Items]
Acquisition-related intangibles, gross carrying amount	2,132		2,135
Acquisition-related intangibles, accumulated amortization	766		714
Acquisition-related intangibles, net	1,366		1,421
Developed technology \| Minimum
Acquired Finite Lived Intangible Assets [Line Items]
Acquisition-related intangibles, amortization period	5 years
Developed technology \| Maximum
Acquired Finite Lived Intangible Assets [Line Items]
Acquisition-related intangibles, amortization period	10 years
Customer relationships
Acquired Finite Lived Intangible Assets [Line Items]
Acquisition-related intangibles, amortization period	8 years
Acquisition-related intangibles, gross carrying amount	810		810
Acquisition-related intangibles, accumulated amortization	355		330
Acquisition-related intangibles, net	455		480
Other intangibles
Acquired Finite Lived Intangible Assets [Line Items]
Acquisition-related intangibles, amortization period	5 years
Acquisition-related intangibles, gross carrying amount	3		3
Acquisition-related intangibles, accumulated amortization	2		2
Acquisition-related intangibles, net	$ 1		$ 1

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 2

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

+ References

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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