Subsequent Event - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified			1 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Jan. 26, 2012 Issuance of Equity Series A Preferred Stock Noncumulative Preferred Stock
Subsequent Event [Line Items]
Fixed-to-floating rate non-cumulative preferred perpetual stock issued			400,000
Preferred stock, par value	$ 0.01	$ 0.01	$ 0.01
Fixed-to-floating rate non-cumulative preferred perpetual stock issued, liquidation preference			$ 1,000
Net proceeds from issuance of fixed-to-floating rate non-cumulative preferred perpetual stock			$ 394
Fixed dividend rate on preferred stock			7.00%
Fixed dividend rate on preferred stock to be paid, year			2022