Document and Entity Information - shares	9 Months Ended
	Dec. 31, 2016	Jan. 30, 2017
Document And Entity Information
Entity Registrant Name	8X8 INC /DE/
Entity Central Index Key	0001023731
Document Type	10-Q
Document Period End Date	Dec. 31, 2016
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 Common Stock, Shares Outstanding		90,932,838
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2017