Investment Securities (Details Textual) (USD $)	9 Months Ended
	Sep. 30, 2011 Loans Basis_Points Multiple Year	Dec. 31, 2010 Year Basis_Points Multiple
Investment Securities (Textual) [Abstract]
Weighted-average maturity of the available-for-sale investment securities (in years)	5.3	7.4
Weighted-average yields of available-for-sale investment securities	3.25%	3.41%
Weighted-average maturity of the held-to-maturity investment securities (in years)	4.0	6.3
Weighted-average yields of held-to-maturity investment securities	2.20%	2.07%
Securities pledged	$ 21,300,000,000	$ 28,000,000,000
Securities sold under agreements to repurchase	7,000,000,000	9,300,000,000
Unpaid principal balance of investment securities with evidence of credit deterioration at acquisition	429,000,000	485,000,000
Fair value of investment securities with evidence of credit deterioration at acquisition	157,000,000	173,000,000
Tax rate on average yields	35.00%
Non-agency [Member] | Residential [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Losses Total	$ 334,000,000