Document and Entity Information - shares	6 Months Ended
	Sep. 30, 2016	Oct. 21, 2016
Document and Entity Information [Abstract]
Entity Registrant Name	CA, INC.
Entity Central Index Key	0000356028
Document Type	10-Q
Document Period End Date	Sep. 30, 2016
Amendment Flag	false
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--03-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		417,837,016