Document and Entity Information	9 Months Ended
	Sep. 30, 2020 shares
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Period Focus	Q3
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Entity Registrant Name	BigCommerce Holdings, Inc.
Entity Central Index Key	0001626450
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity File Number	001-39423
Entity Tax Identification Number	46-2707656
Entity Address Address Line1	11305 Four Points Drive Building II, 3rd Floor
Entity Address City Or Town	Austin
Entity Address State Or Province	TX
Entity Interactive Data Current	Yes
Entity Address Postal Zip Code	78726
City Area Code	512
Local Phone Number	865-4500
Entity Incorporation State Country Code	DE
Security12b Title	Series 1 common stock, $0.0001 par value per share
Trading Symbol	BIGC
Security Exchange Name	NASDAQ
Series 1 Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding	62,756,186
Series 2 Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding	5,050,555