Consolidated Balance Sheets (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012
ASSETS
Cash and due from banks	$ 621		$ 584		$ 415
Short-term investments	3,081		3,940		3,605
Trading account assets	701		605		614
Securities available for sale	13,496		12,094		14,633
Held-to-maturity securities (fair value: $3,779, $3,992 and $3,052)	3,721		3,931		3,019
Other investments	1,059		1,064		1,188
Loans, net of unearned income of $923, $957 and $1,282	52,574		52,822		49,226
Less: Allowance for loan and lease losses	893		888		944
Net loans	51,681		51,934		48,282
Loans held for sale	434		599		511
Premises and equipment	930		965		937
Operating lease assets	309		288		335
Goodwill	979		979		917
Other intangible assets	159		171		15
Corporate-owned life insurance	3,352		3,333		3,270
Derivative assets	609		693		830
Accrued income and other assets (including $50 of consolidated LIHTC guaranteed funds VIEs, see Note 9)	2,884	[1]	2,774	[1]	3,070	[1]
Discontinued assets (including $2,358 of consolidated education loan securitization trust VIEs (see Note 9) and $154 of loans in portfolio at fair value)	5,182	[1]	5,282	[1]	5,790	[1]
Total assets	89,198		89,236		87,431
Deposits in domestic offices:
NOW and money market deposit accounts	32,700		32,380		29,124
Savings deposits	2,546		2,433		2,075
Certificates of deposit ($100,000 or more)	2,998		2,879		3,984
Other time deposits	4,324		4,575		5,848
Total interest-bearing	42,568		42,267		41,031
Noninterest-bearing	21,564		23,319		19,606
Deposits in foreign office - interest-bearing	522		407		857
Total deposits	64,654		65,993		61,494
Federal funds purchased and securities sold under repurchase agreements	1,950		1,609		1,846
Bank notes and other short-term borrowings	378		287		324
Derivative liabilities	524		584		754
Accrued expense and other liabilities	1,352		1,387		1,424
Long-term debt	7,785		6,847		8,898
Discontinued liabilities (including $2,151 of consolidated education loan securitization trust VIEs at fair value, see Note 9)	2,176	[1]	2,220	[1]	2,575	[1]
Total liabilities	78,819		78,927		77,315
Preferred stock, $1 par value, authorized 25,000,000 shares:
Common shares, $1 par value; authorized 1,400,000,000 shares; issued 1,016,969,905, 1,016,969,905 and 1,016,969,905 shares	1,017		1,017		1,017
Capital surplus	4,059		4,126		4,116
Retained earnings	7,065		6,913		6,411
Treasury stock, at cost (94,388,605, 91,201,285 and 60,868,267)	(1,930)		(1,952)		(1,717)
Accumulated other comprehensive income (loss)	(162)		(124)		(19)
Key shareholders' equity	10,340		10,271		10,099
Noncontrolling interests	39		38		17
Total equity	10,379		10,309		10,116
Total liabilities and equity	89,198		89,236		87,431
Series A Preferred Stock [Member]
Preferred stock, $1 par value, authorized 25,000,000 shares:
Preferred stock	$ 291		$ 291		$ 291

[1] The assets of the VIEs can only be used by the particular VIE and there is no recourse to Key with respect to the liabilities of the consolidated LIHTC or education loan securitization trust VIEs.