Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2021	Feb. 17, 2022	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2021
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36189
Entity Registrant Name	Tandem Diabetes Care, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-4327508
Entity Address, Address Line One	11075 Roselle Street
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	366-6900
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	TNDM
Security Exchange Name	NASDAQ
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
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 5.4
Entity Common Stock, Shares Outstanding (in shares)		63,872,310
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement for the 2022 Annual Meeting of Stockholders, to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Form 10-K, are incorporated by reference in Part III, Items 10-14 of this Form 10-K. Except for the portions of the Proxy Statement specifically incorporated by reference in this Form 10-K, the Proxy Statement shall not be deemed to be filed as part hereof.
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Central Index Key	0001438133