Cover Page - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Feb. 21, 2020	Jun. 30, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	001-37918
Entity Registrant Name	iRhythm Technologies, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8149544
Entity Address, Address Line One	699 8th Street
Entity Address, Address Line Two	Suite 600
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94103
City Area Code	415
Local Phone Number	632-5700
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
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 Public Float			$ 1,950,000
Entity Common Stock, Shares Outstanding		26,801,044
Documents Incorporated by Reference	Portions of the information called for by Part III of this Form 10-K is hereby incorporated by reference from the definitive Proxy Statements for our annual meeting of stockholders, which will be filed with the Securities and Exchange Commission not later than 120 days after December 31, 2019.
Title of 12(b) Security	Common Stock, Par Value $.001 Per Share
Trading Symbol	IRTC
Security Exchange Name	NASDAQ
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Central Index Key	0001388658
Current Fiscal Year End Date	--12-31