Acquisition, Divestiture and Discontinued Operations (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009	Dec. 31, 2008
Components of Income (Loss) from Discontinued Operations, Net of Taxes, of Subsidiary
Noninterest income	$ 1,808		$ 1,954		$ 2,035
Intangible assets impairment					241
Other noninterest expense	366		474		460
Income (loss) before income taxes	(70)		(37)		(76)
Income taxes	369		186		(1,035)
Income (loss) from discontinued operations, net of taxes	(44)		(23)		(48)
Components of Assets and Liabilities of Subsidiaries
Cash and due from banks	694		278		471	1,245
Total assets	5,860	[1]	6,554	[1]
Total liabilities	2,550	[1]	2,998	[1]
Austin Capital Management [Member]
Components of Income (Loss) from Discontinued Operations, Net of Taxes, of Subsidiary
Income (loss) before income taxes	(1)		(1)		(9)
Income (loss) from discontinued operations, net of taxes	(1)		(1)		(6)
Components of Assets and Liabilities of Subsidiaries
Total assets	31		33
Total liabilities	0		1
Community Banking [Member]
Components of Income (Loss) from Discontinued Operations, Net of Taxes, of Subsidiary
Noninterest income	746		772		758
Income taxes	36		4		(120)
Segment, Discontinued Operations [Member]
Components of Income (Loss) from Discontinued Operations, Net of Taxes, of Subsidiary
Noninterest income	(54)		(61)		49
Intangible assets impairment	0				27
Income taxes	(26)		(14)		(28)
Components of Assets and Liabilities of Subsidiaries
Cash and due from banks	31		33
Segment, Discontinued Operations [Member] | Austin Capital Management [Member]
Components of Income (Loss) from Discontinued Operations, Net of Taxes, of Subsidiary
Noninterest income	1		5		26
Intangible assets impairment	0				27
Other noninterest expense	2		6		8
Income taxes	0				(3)
Components of Assets and Liabilities of Subsidiaries
Cash and due from banks	31		33
Accrued expense and other liabilities	$ 0		$ 1

[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.