Income taxes (Details 1) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax assets:
NOL and credit carryforwards	$ 1,017	$ 427
Expense accruals	697	805
Expenses capitalized for tax	196	195
Stock-based compensation	211	115
Deferred revenue	40	40
Other	104	83
Total deferred income tax assets	2,265	1,665
Valuation allowance	(314)	(273)
Net deferred income tax assets	1,951	1,392
Deferred income tax liabilities:
Acquired intangibles	(4,430)	(1,249)
Fixed assets	(8)	(117)
Unremitted foreign earnings	(55)	(106)
Other	(200)	(145)
Total deferred income tax liabilities	(4,693)	(1,617)
Total deferred income taxes, net	$ (2,742)	$ (225)