Investment Securities (Details Textual) (USD $)	6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Investment Securities (Textuals) [Abstract]
Weighted-average maturity of the available-for-sale investment securities (in years)	7.4	7.4
Weighted-average yields of available-for-sale investment securities	3.33%	3.41%
Weighted-average maturity of the held-to-maturity investment securities (in years)	5.2	6.3
Weighted-average yields of held-to-maturity investment securities	2.26%	2.07%
Securities pledged	$ 22,700,000,000	$ 28,000,000,000
Securities sold under agreements to repurchase	7,200,000,000	9,300,000,000
Unpaid principal balance of investment securities with evidence of credit deterioration at acquisition	443,000,000	485,000,000
Certain Investment securities acquired in Transfer Accounted for as Debt Securities, Acquired During Period, at Acquisition, at Fair Value	$ 168,000,000	$ 173,000,000
Tax rate on Average yields	35.00%