Preferred Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Number of shares issued and outstanding and carrying amount of preferred stock
Shares Issued and Outstanding	159,910	72,510
Liquidation Preference	$ 4,936	$ 2,751
Discount	167	145
Carrying Amount	4,769	2,606
Series A [Member]
Number of shares issued and outstanding and carrying amount of preferred stock
Shares Issued and Outstanding	12,510	12,510
Liquidation Preference	1,251	1,251
Discount	145	145
Carrying Amount	1,106	1,106
Series B [Member]
Number of shares issued and outstanding and carrying amount of preferred stock
Shares Issued and Outstanding	40,000	40,000
Liquidation Preference	1,000	1,000
Discount
Carrying Amount	1,000	1,000
Series D [Member]
Number of shares issued and outstanding and carrying amount of preferred stock
Shares Issued and Outstanding	20,000	20,000
Liquidation Preference	500	500
Discount
Carrying Amount	500	500
Series F [Member]
Number of shares issued and outstanding and carrying amount of preferred stock
Shares Issued and Outstanding	44,000
Liquidation Preference	1,100
Discount	12
Carrying Amount	1,088
Series G [Member]
Number of shares issued and outstanding and carrying amount of preferred stock
Shares Issued and Outstanding	43,400
Liquidation Preference	1,085
Discount	10
Carrying Amount	$ 1,075