Investment Securities (Details Textuals) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended		3 Months Ended			6 Months Ended			3 Months Ended	6 Months Ended	3 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Mar. 31, 2011	Jun. 30, 2011 Mortgage-backed securities sold that were guaranteed by Fannie Mae and Freddie Mac [Member]	Mar. 31, 2011 Mortgage-backed securities sold that were guaranteed by Fannie Mae and Freddie Mac [Member]	Jun. 30, 2011 Privately issued residential mortgage-backed securities [Member]	Jun. 30, 2011 Privately issued residential mortgage-backed securities [Member]	Jun. 30, 2011 Trust preferred securities [Member]	Jun. 30, 2011 Collateralized Debt Obligations [Member]	Jun. 30, 2010 Investment securities [Member]	Jun. 30, 2010 Investment securities [Member]	Jun. 30, 2010 American depositary shares [Member]
Investment securities (Textuals) [Abstract]
Gross realized gains on investment securities	$ 111,000,000		$ 150,000,000
Gross realized losses on investment securities	0	0	0	0
Aggregate amortized cost on mortgage-backed securities							1,000,000,000	484,000,000			136,000,000	100,000,000
Pre-tax gain on sale of mortgage-backed securities							66,000,000	39,000,000			25,000,000	20,000,000
Pre-tax other-than-temporary impairment losses									27,000,000	43,000,000			22,000,000	49,000,000	12,000,000
Number of investment securities with aggregate gross unrealized losses						387
Unrealized losses on individual investment securities			350,845,000		426,828,000
Unrealized losses on privately issued residential mortgage-backed securities			211,000,000
Residential mortgage-backed securities at cost	1,200,000,000		1,200,000,000		1,500,000,000
Unrealized losses on trust preferred securities issued by financial institutions and securities backed by trust preferred securities			29,000,000
Other debt securities at cost	191,000,000		191,000,000
Other debt securities, fair value	$ 382,090,000		$ 382,090,000		$ 412,709,000