Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2017	Mar. 31, 2017
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jan. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	COUP
Entity Registrant Name	Coupa Software Inc
Entity Central Index Key	0001385867
Current Fiscal Year End Date	--01-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		50,495,239
Entity Public Float	$ 638.3