Cover - shares shares in Millions	3 Months Ended
	Mar. 31, 2022	May 02, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	001-39546
Entity Registrant Name	Proterra Inc
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	98-1551379
Entity Address, Address Line One	1815 Rollins Road
Entity Address, City or Town	Burlingame
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94010
City Area Code	864
Local Phone Number	438-0000
Title of 12(b) Security	Common Stock, $0.0001 par value per share
Trading Symbol	PTRA
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		223.0
Entity Central Index Key	0001820630
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1