Document and Entity Information (USD $)	12 Months Ended
	Mar. 31, 2015	Sep. 30, 2015	May 27, 2015
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, 2015
Amendment Flag	false
Current Fiscal Year End Date	--03-31
Is Entity a Well-known Seasoned Issuer?	Yes
Is Entity a Voluntary Filer?	No
Is Entity's Reporting Status Current?	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float		$ 587,802,739
Entity Common Stock, Shares Outstanding			88,152,273
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2015