Acquisition, Divestiture and Discontinued Operations (Details 7) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2008
Combined assets and liabilities of the discontinued operations
Cash and due from banks	$ 694		$ 278		$ 471	$ 1,245
Loans, net of unearned income of ($2) and $1	49,575		50,107
Less: Allowance for loan and lease losses	1,004		1,604
Net loans	48,571		48,503
Loans held for sale	728		467		443
Trust accrued income and other assets at fair value	3,077	[1]	3,876	[1]
Total assets	5,860	[1]	6,554	[1]
Accrued expense and other liabilities	1,763		1,931
Total liabilities	2,550	[1]	2,998	[1]
Segment, Discontinued Operations [Member]
Combined assets and liabilities of the discontinued operations
Cash and due from banks	31		33
Loans, net of unearned income of ($2) and $1	3,010		3,326
Less: Allowance for loan and lease losses	104		114
Net loans	5,708		6,337
Loans held for sale	0		15
Accrued expense and other liabilities	0		1
Segment, Discontinued Operations [Member] | Trust [Member]
Combined assets and liabilities of the discontinued operations
Trust Loans at fair value	2,726		3,125
Trust accrued income and other assets at fair value	121		169
Accrued expense and other liabilities	28		31
Trust securities at fair value	2,522		2,966
Segment, Discontinued Operations [Member] | Portfolio [Member]
Combined assets and liabilities of the discontinued operations
Trust Loans at fair value	$ 76		$ 0

[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.