Securities (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2011
SECURITIES AVAILABLE FOR SALE
Amortized Cost	$ 12,768	$ 15,490	$ 18,117
Gross Unrealized Gains	438	522	563
Gross Unrealized Losses	1
Fair Value	13,205	16,012	18,680
HELD-TO-MATURITY SECURITIES
Held-to-maturity securities	4,352	2,109	19
Held-to-maturity Securities, Unrecognized Holding Gains	44	24
Held-to-maturity Securities, Unrecognized Holding Losses
Held-to-maturity securities, fair value	4,396	2,133	19
US Treasury and Government [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost			9
Fair Value			9
States and political subdivisions [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	53	60	126
Gross Unrealized Gains	3	3	3
Gross Unrealized Losses
Fair Value	56	63	129
HELD-TO-MATURITY SECURITIES
Held-to-maturity securities			1
Held-to-maturity securities, fair value			1
Collateralized mortgage obligations [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	12,098	14,707	17,124
Gross Unrealized Gains	379	455	485
Gross Unrealized Losses
Fair Value	12,477	15,162	17,609
HELD-TO-MATURITY SECURITIES
Held-to-maturity securities	4,334	2,091
Held-to-maturity Securities, Unrecognized Holding Gains	44	24
Held-to-maturity Securities, Unrecognized Holding Losses
Held-to-maturity securities, fair value	4,378	2,115
Other mortgage-backed securities [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	597	715	845
Gross Unrealized Gains	55	63	72
Gross Unrealized Losses
Fair Value	652	778	917
Other securities [Member]
SECURITIES AVAILABLE FOR SALE
Amortized Cost	20	8	13
Gross Unrealized Gains	1	1	3
Gross Unrealized Losses	1
Fair Value	20	9	16
HELD-TO-MATURITY SECURITIES
Held-to-maturity securities	18	18	18
Held-to-maturity Securities, Unrecognized Holding Gains
Held-to-maturity Securities, Unrecognized Holding Losses
Held-to-maturity securities, fair value	$ 18	$ 18	$ 18

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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