Agreements with Royalty Pharma - Schedule Represents Allocation of Transaction Consideration on a Relative Fair Value Basis to the Liability and the Common Stock (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
RP Aficamten Liability [Member]
Royalty Liability [Line Items]
Liabilities related to revenue participation right purchase agreements, net beginning balance	$ 262,599	$ 180,591	$ 105,117
Additional consideration	0	0	50,000
Modification in 2024 RPI transactions	0	33,300	0
Interest accretion	58,165	48,708	25,474
Amortization of issuance costs	0	0	0
Liabilities related to revenue participation right purchase agreements, net ending balance	320,764	262,599	180,591
RPOM Liability [Member]
Royalty Liability [Line Items]
Liabilities related to revenue participation right purchase agreements, net beginning balance	199,593	199,384	195,384
Additional consideration		0	0
Modification in 2024 RPI transactions	0	0	0
Interest accretion	124	103	3,888
Amortization of issuance costs	78	106	112
Liabilities related to revenue participation right purchase agreements, net ending balance	$ 199,795	$ 199,593	$ 199,384

CYTOKINETICS INC 10-K