Acquisitions - Aggregate Consideration Paid (Details) - USD ($) $ in Millions		3 Months Ended
	Jul. 15, 2019	Mar. 31, 2018
Nuevolution
Business Acquisition [Line Items]
Total consideration transferred to acquire K-A	$ 183
Kirin-Amgen, Inc. (K-A)
Business Acquisition [Line Items]
Total cash paid to Kirin		$ 780
Fair value of contingent consideration obligation		45
Loss on settlement of preexisting relationship		(168)
Total consideration transferred to acquire K-A		657
Fair value of Amgen’s investment in K-A		825
Total acquisition date fair value		$ 1,482
R & D Technology rights | Nuevolution
Business Acquisition [Line Items]
Weighted average period of amortization	10 years