Document and Entity Information (USD $)	12 Months Ended
	Dec. 31, 2012	Feb. 25, 2013
Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2012
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY
Trading Symbol	KEY
Entity Registrant Name	KEYCORP /NEW/
Entity Central Index Key	0000091576
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		923,858,672
Entity Public Float	$ 7,317,963,768