Securities (Gross Unrealized Losses and Fair Values of Investments by Investment Category and Length of Time) (Details) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010
Fair value of temporarily impaired available for sale securities, less than 12 months	$ 10,620	$ 16,796
Unrealized losses on temporarily impaired available for sale securities, less than 12 months	118	386
Fair value of temporarily impaired available for sale securities, 12 months or more	1,079	1,243
Unrealized losses on temporarily impaired available for sale securities, 12 months or more	211	260
Total fair value of temporarily impaired available for sale securities	11,699	18,039
Total unrealized losses on temporarily impaired available for sale securities	329	646
Fair value of temporarily impaired held to maturity securities, less than 12 months	91
Unrealized losses on temporarily impaired held to maturity securities, less than 12 months	1
Total fair value of temporarily impaired held to maturity securities	91
Total unrealized losses on temporarily impaired held to maturity securities	1
U.S. Government-Sponsored Entities ("GSE") [Member]
Fair value of temporarily impaired available for sale securities, less than 12 months		50
Total fair value of temporarily impaired available for sale securities		50
Mortgage-Backed Securities Issued by GSE [Member]
Fair value of temporarily impaired available for sale securities, less than 12 months	10,312	15,438
Unrealized losses on temporarily impaired available for sale securities, less than 12 months	107	361
Total fair value of temporarily impaired available for sale securities	10,312	15,438
Total unrealized losses on temporarily impaired available for sale securities	107	361
States and Political Subdivisions [Member]
Fair value of temporarily impaired available for sale securities, less than 12 months	258	694
Unrealized losses on temporarily impaired available for sale securities, less than 12 months	7	21
Fair value of temporarily impaired available for sale securities, 12 months or more	655	735
Unrealized losses on temporarily impaired available for sale securities, 12 months or more	114	140
Total fair value of temporarily impaired available for sale securities	913	1,429
Total unrealized losses on temporarily impaired available for sale securities	121	161
Fair value of temporarily impaired held to maturity securities, less than 12 months	32
Total fair value of temporarily impaired held to maturity securities	32
Non-Agency Mortgage-Backed Securities [Member]
Fair value of temporarily impaired available for sale securities, 12 months or more	424	506
Unrealized losses on temporarily impaired available for sale securities, 12 months or more	97	120
Total fair value of temporarily impaired available for sale securities	424	506
Total unrealized losses on temporarily impaired available for sale securities	97	120
Other Securities [Member]
Fair value of temporarily impaired available for sale securities, less than 12 months	1	535
Unrealized losses on temporarily impaired available for sale securities, less than 12 months		2
Fair value of temporarily impaired available for sale securities, 12 months or more		2
Total fair value of temporarily impaired available for sale securities	1	537
Total unrealized losses on temporarily impaired available for sale securities		2
Fair value of temporarily impaired held to maturity securities, less than 12 months	59
Unrealized losses on temporarily impaired held to maturity securities, less than 12 months	1
Total fair value of temporarily impaired held to maturity securities	59
Total unrealized losses on temporarily impaired held to maturity securities	1
Covered Securities [Member]
Fair value of temporarily impaired available for sale securities, less than 12 months	49	79
Unrealized losses on temporarily impaired available for sale securities, less than 12 months	4	2
Total fair value of temporarily impaired available for sale securities	49	79
Total unrealized losses on temporarily impaired available for sale securities	$ 4	$ 2

This item represents the excess of amortized cost basis over fair value of securities that have been in a loss position for twelve months or longer for those securities which are categorized neither as held-to-maturity nor trading securities.

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