Cover Page - shares	9 Months Ended
	Sep. 30, 2024	Oct. 25, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	000-30739
Entity Registrant Name	INSMED INC
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	54-1972729
Entity Address, Address Line One	700 US Highway 202/206
Entity Address, City or Town	Bridgewater
Entity Address, State or Province	NJ
Entity Address, Postal Zip Code	08807
City Area Code	908
Local Phone Number	977-9900
Title of 12(b) Security	Common stock, par value $0.01 per share
Trading Symbol	INSM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		178,902,721
Entity Central Index Key	0001104506
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3