Regulatory Matters (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2012
Regulatory Capital Requirements [Abstract]
Minimum tier 1 risk-based capital ratio to be considered "well-capitalized"	6.00%
Minimum total risk-based capital ratio to be considered "well-capitalized"	10.00%
Tier 1 leverage ratio to be considered "well-capitalized"	5.00%
Average aggregate cash balances to satisfy reserve requirements	$ 4,100,000,000
Undistributed earnings	1,940,000,000
Maximum credit to any one affiliate as a percentage on its capital	10.00%
Maximum credit to all affiliates as a percentage on its capital	20.00%
Undistributed earnings of unconsolidated entities	$ 453,000,000

Average aggregate cash balances to satisfy reserve requirements

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- Definition

Maximum Credit To All Affiliates As Percentage On Its Capital

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Maximum Credit To Any One Affiliate As Percentage On Its Capital

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- Definition

Undistributed earnings of unconsolidated entities

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- Definition

The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Paragraph 15

-Subparagraph 3a

-IssueDate 2006-05-01

-Chapter 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Paragraph 22

-IssueDate 2006-05-01

-Chapter 17

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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- Definition

The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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- Definition

Earnings allocated (not distributed) to participating securities under the two-class method to the extent that participating securities may share in earnings as if all of the earnings for the period had been distributed.

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