Shareholders' Equity (Details) (USD $) In Millions, except Share data	6 Months Ended
	Jun. 30, 2011
Summary of perpetual preferred stock issued and outstanding
Shares Issued	124,000
Shares Authorized	185,000
Shares Outstanding	123,998
Redemption Value	$ 3,100
Series A Preferred Stock [Member]
Summary of perpetual preferred stock issued and outstanding
Shares Issued	30,000
Shares Authorized	50,000
Shares Outstanding	29,999
Dividend Rate	3 month LIBOR + 0.75%, with floor of 3.75% per annum
Earliest Redemption Date	Apr. 25, 2010
Redemption Value	750
Series B Preferred Stock [Member]
Summary of perpetual preferred stock issued and outstanding
Shares Issued	32,000
Shares Authorized	50,000
Shares Outstanding	32,000
Dividend Rate	6.20% per annum
Earliest Redemption Date	Oct. 31, 2010
Redemption Value	800
Series C Preferred Stock [Member]
Summary of perpetual preferred stock issued and outstanding
Shares Issued	8,000
Shares Authorized	25,000
Shares Outstanding	8,000
Dividend Rate	3 month LIBOR + 0.75%, with floor of 4.00% per annum
Earliest Redemption Date	Oct. 31, 2010
Redemption Value	200
Series D Preferred Stock [Member]
Summary of perpetual preferred stock issued and outstanding
Shares Issued	54,000
Shares Authorized	60,000
Shares Outstanding	53,999
Dividend Rate	3 month LIBOR + 0.67%, with floor of 4.00% per annum
Earliest Redemption Date	May 24, 2011
Redemption Value	$ 1,350