Acquisition and Discontinued Operations (Details 7) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011		Jun. 30, 2011		Dec. 31, 2010
Components of Assets and Liabilities of Subsidiary
Cash and due from banks	$ 717		$ 694		$ 853		$ 278
Total assets	5,533	[1]	5,860	[1]	6,328	[1]
Total liabilities	2,401	[1]	2,550	[1]	2,950	[1]
Segment, Discontinued Operations [Member]
Components of Assets and Liabilities of Subsidiary
Cash and due from banks	22		31		32
Total liabilities	2,401		2,550		2,950
Segment, Discontinued Operations [Member] | Austin Capital Management [Member]
Components of Assets and Liabilities of Subsidiary
Cash and due from banks	22		31		32
Total assets	22		31		32
Accrued expense and other liabilities					1
Total liabilities					$ 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.