Stockholders' equity (Components of AOCI) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Increase (Decrease) in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance, Foreign currency translation	$ (264)
Beginning balance, Cash flow hedges	290
Beginning balance, Available-for-sale securities	(19)
Beginning balance, Other	(15)
Beginning balance, AOCI	(8)
Other Comprehensive Income (Loss), before Tax [Abstract]
Foreign currency translation adjustments	(184)
Unrealized gains (losses), Cash flow hedges	168
Unrealized gains (losses), Available-for-sale securities	188
Unrealized gains (losses), Other	0
Unrealized gains (losses), AOCI	356
Reclassification adjustments to income, Cash flow hedges	114
Reclassification adjustments to income, Available-for-sale securities	35
Reclassification adjustments to income, AOCI	149
Income taxes, Foreign currency translation	11
Income taxes, Cash flow hedges	(104)
Income taxes, Available-for-sale securities	(83)
Income taxes, Other	0amgn_OtherComprehensiveIncomeOtherTax
Income taxes, AOCI	(176)us-gaap_OtherComprehensiveIncomeLossTax
Ending balance, Foreign currency translation	(437)
Ending balance, Cash flow hedges	468
Ending balance, Available-for-sale securities	121
Ending balance, Other	(15)
Ending balance, AOCI	$ 137

Accumulated other comprehensive income or loss, other items net of tax.

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Tax effect of other comprehensive income net of reclassification adjustments.

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Total other comprehensive income reclassification adjustment to income before tax.

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Unrealized other comprehensive gain (loss) arising during period on other items, before reclassifications and tax.

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Aggregate unrealized (losses)/gains arising during the period, before reclassifications and taxes.

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Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

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Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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Accumulated adjustment, net of tax, that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency from the functional currency of the reporting entity, net of reclassification of realized foreign currency translation gains or losses.

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount before tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount of tax expense (benefit), before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount of tax expense (benefit), after reclassification adjustments, of appreciation (loss) in value of unsold available-for-sale securities. Excludes amounts related to other than temporary impairment (OTTI) loss.

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Amount before tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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Amount before tax and reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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