Investment Securities (Critical Estimates Used In Roll Rate Analysis) (Details)	Sep. 30, 2011		Dec. 31, 2010
Sub-Prime [Member] | Maximum [Member]
Prepayment rate	3.00%		3.00%
Cumulative loss estimates	54.00%
Loss severity	72.00%
Peak-to-trough housing price decline			40.00%
Alt-A [Member] | Maximum [Member]
Prepayment rate	5.00%
Cumulative loss estimates	39.00%
Loss severity	61.00%
Peak-to-trough housing price decline			40.00%
Non-Agency Prime [Member] | Maximum [Member]
Prepayment rate	8.00%		10.00%
Cumulative loss estimates	19.00%
Loss severity	54.00%
Peak-to-trough housing price decline			40.00%
Sub-Prime [Member] | Minimum [Member]
Prepayment rate	1.00%		2.00%
Cumulative loss estimates	46.00%
Loss severity	70.00%
Peak-to-trough housing price decline			35.00%
Alt-A [Member] | Minimum [Member]
Prepayment rate	3.00%
Cumulative loss estimates	26.00%
Loss severity	59.00%
Peak-to-trough housing price decline			35.00%
Non-Agency Prime [Member] | Minimum [Member]
Prepayment rate	6.00%		7.00%
Cumulative loss estimates	10.00%
Loss severity	52.00%
Peak-to-trough housing price decline			35.00%
Sub-Prime [Member]
Prepayment rate	0.00%
Cumulative loss estimates	0.00%		33.00%
Loss severity	0.00%	[1]	67.00%	[1]
Peak-to-trough housing price decline	36.00%	[2]
Alt-A [Member]
Prepayment rate	0.00%		7.00%
Cumulative loss estimates	0.00%		21.00%
Loss severity	0.00%	[1]	49.00%	[1]
Peak-to-trough housing price decline	36.00%	[2]
Non-Agency Prime [Member]
Prepayment rate	0.00%
Cumulative loss estimates	0.00%		13.00%
Loss severity	0.00%	[1]	49.00%	[1]
Peak-to-trough housing price decline	36.00%	[2]

[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.