| Document and Entity Information | Jul. 27, 2021 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | AMGEN INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000318154 |
| Document Type | 8-K |
| Document Period End Date | Jul. 27, 2021 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-37702 |
| Entity Tax Identification Number | 95-3540776 |
| Entity Address, Address Line One | One Amgen Center Drive |
| Entity Address, City or Town | Thousand Oaks |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 91320-1799 |
| City Area Code | (805) |
| Local Phone Number | 447-1000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common stock, $0.0001 par value |
| Trading Symbol | AMGN |
| Security Exchange Name | NASDAQ |
| A 1.250 Senior Notes Due 2022 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.250% Senior Notes Due 2022 |
| Trading Symbol | AMGN22 |
| Security Exchange Name | NASDAQ |
| A 2.00 Senior Notes Due 2026 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 2.000% Senior Notes Due 2026 |
| Trading Symbol | AMGN26 |
| Security Exchange Name | NASDAQ |
