Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Mar. 31, 2019	May 16, 2019	Sep. 30, 2018
Document And Entity Information
Entity Registrant Name	8X8 INC /DE/
Entity Central Index Key	0001023731
Document Type	10-K
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--03-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 2.0
Entity Common Stock, Shares Outstanding		96,287,366
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019