Goodwill and acquisition-related intangibles - Acquisition-related intangibles (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets, Net [Abstract]
Acquisition-related intangibles, gross carrying amount	$ 2,948	$ 2,991
Acquisition-related intangibles, accumulated amortization	1,046	768
Acquisition-related intangibles, net	1,902us-gaap_FiniteLivedIntangibleAssetsNet	2,223us-gaap_FiniteLivedIntangibleAssetsNet
Amortization of acquisition-related intangibles	321us-gaap_AmortizationOfIntangibleAssets	336us-gaap_AmortizationOfIntangibleAssets	342us-gaap_AmortizationOfIntangibleAssets
Finite-Lived Intangible Assets, Future Amortization Expense [Abstract]
2015	319
2016	319
2017	318
2018	318
2019	288
Thereafter	340
Developed technology
Finite-Lived Intangible Assets, Net [Abstract]
Acquisition-related intangibles, gross carrying amount	2,135	2,157
Acquisition-related intangibles, accumulated amortization	714	526
Acquisition-related intangibles, net	1,421	1,631
Customer relationships
Finite-Lived Intangible Assets, Net [Abstract]
Acquisition-related intangibles, amortization period	8 years
Acquisition-related intangibles, gross carrying amount	810	821
Acquisition-related intangibles, accumulated amortization	330	239
Acquisition-related intangibles, net	480	582
Other intangibles
Finite-Lived Intangible Assets, Net [Abstract]
Acquisition-related intangibles, amortization period	5 years
Acquisition-related intangibles, gross carrying amount	3	5
Acquisition-related intangibles, accumulated amortization	2	3
Acquisition-related intangibles, net	1	2
In-process R&D
Finite-Lived Intangible Assets, Net [Abstract]
Acquisition-related intangibles, gross carrying amount	0	8
Acquisition-related intangibles, net	$ 0	$ 8
Minimum \| Developed technology
Finite-Lived Intangible Assets, Net [Abstract]
Acquisition-related intangibles, amortization period	5 years
Maximum \| Developed technology
Finite-Lived Intangible Assets, Net [Abstract]
Acquisition-related intangibles, amortization period	10 years

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.

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)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

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

+ Details

Name:	us-gaap_AmortizationOfIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

+ Details

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

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized 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.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of amortization expense for assets, excluding financial assets and goodwill, lacking physical substance with a finite life expected to be recognized during 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.

+ References