Investment Securities (Critical Estimates Used In Roll Rate Analysis) (Details)	Dec. 31, 2011		Dec. 31, 2010
Sub-Prime [Member]
Cumulative loss estimates			33.00%
Loss severity			67.00%	[1]
Peak-to-trough housing price decline	35.00%	[2]
Alt-A [Member]
Prepayment rate			7.00%
Cumulative loss estimates			21.00%
Loss severity			49.00%	[1]
Peak-to-trough housing price decline	35.00%	[2]
Non-Agency Prime [Member]
Cumulative loss estimates			13.00%
Loss severity			49.00%	[1]
Peak-to-trough housing price decline	35.00%	[2]
Maximum [Member] | Sub-Prime [Member]
Prepayment rate	3.00%		3.00%
Cumulative loss estimates	54.00%
Loss severity	72.00%
Peak-to-trough housing price decline			40.00%
Maximum [Member] | Alt-A [Member]
Prepayment rate	6.00%
Cumulative loss estimates	39.00%
Loss severity	61.00%
Peak-to-trough housing price decline			40.00%
Maximum [Member] | Non-Agency Prime [Member]
Prepayment rate	10.00%		10.00%
Cumulative loss estimates	19.00%
Loss severity	53.00%
Peak-to-trough housing price decline			40.00%
Minimum [Member] | Sub-Prime [Member]
Prepayment rate	1.00%		2.00%
Cumulative loss estimates	46.00%
Loss severity	70.00%
Peak-to-trough housing price decline			35.00%
Minimum [Member] | Alt-A [Member]
Prepayment rate	2.00%
Cumulative loss estimates	26.00%
Loss severity	59.00%
Peak-to-trough housing price decline			35.00%
Minimum [Member] | Non-Agency Prime [Member]
Prepayment rate	5.00%		7.00%
Cumulative loss estimates	9.00%
Loss severity	52.00%
Peak-to-trough housing price decline			35.00%

[1] Loss severity rates consider the initial loan-to-value ratio, lien position, geography, expected collateral value and other factors.

[2] Management's expectation of the Case-Shiller National Home Price Index.