Long-Term Debt (Long-Term Debt Portfolio) (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Debt Instrument [Line Items]
Due within one year	$ 25,938,000,000	$ 26,185,000,000
Due after one year	65,988,000,000	65,551,000,000
Derivative, Amount of Hedged Item	1,102,000,000	1,058,000,000
Long-term debt	93,028,000,000	92,794,000,000
Long-term debt guaranteed by the Federal Deposit Insurance Corporation	7,400,000,000	7,400,000,000
Long-term debt, fair value elected	0	830,000,000
Unsecured Debt [Member]
Debt Instrument [Line Items]
Due within one year	8,886,000,000	11,664,000,000
Due after one year	32,429,000,000	30,272,000,000
Derivative, Amount of Hedged Item	1,102,000,000	1,058,000,000
Long-term debt	42,417,000,000	42,994,000,000
Secured Debt [Member]
Debt Instrument [Line Items]
Due within one year	17,052,000,000	14,521,000,000
Due after one year	33,559,000,000	35,279,000,000
Derivative, Amount of Hedged Item	0	0
Long-term debt	50,611,000,000	49,800,000,000
Trust Preferred Securities Subject to Mandatory Redemption [Member]
Debt Instrument [Line Items]
Due after one year	$ 2,600,000,000	$ 2,600,000,000