Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2024	Nov. 08, 2024
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-34475
Entity Registrant Name	OMEROS CORPORATION
Entity Incorporation, State or Country Code	WA
Entity Tax Identification Number	91-1663741
Entity Address, Address Line One	201 Elliott Avenue West
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98119
City Area Code	206
Local Phone Number	676-5000
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	OMER
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		57,949,760
Entity Central Index Key	0001285819
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false