Securities Sold Under Agreements To Repurchase (Schedule Of Long-Term Securities Sold Under Agreements To Repurchase) (Details) (USD $)	9 Months Ended
Sep. 30, 2011
Schedule of Investments [Line Items]
Floating Rate, Rate index, 8% minus 3 month LIBOR	8.00%
No. of agreements	27
Amount	$ 1,400,000,000
Weighted average rate	4.14%
2014 [Member] \| Fixed To Floating 50.0 With 1 Agreement At 3.53% [Member] \| Fixed-To-Floating [Member]
Schedule of Investments [Line Items]
Maximum rate	3.53%
Minimum rate	0.00%
No. of agreements	1
Amount	50,000,000
Weighted average rate	3.53%
Final maturity	2,014
2015 [Member] \| Fixed To Floating 50.0 With 1 Agreement At 3.53% [Member] \| Fixed-To-Floating [Member]
Schedule of Investments [Line Items]
Maximum rate	3.53%
Minimum rate	0.00%
No. of agreements	1
Amount	50,000,000
Weighted average rate	3.53%
Final maturity	2,015
Fixed To Floating 150.0 Million With 3 Agreements At 3.75% [Member] \| Fixed-To-Floating [Member]
Schedule of Investments [Line Items]
Maximum rate	3.75%
Minimum rate	0.00%
No. of agreements	3
Amount	150,000,000
Weighted average rate	3.75%
Final maturity	2,014
Fixed-To-Floating 200.0 [Member] \| Fixed-To-Floating [Member]
Schedule of Investments [Line Items]
Maximum rate	3.50%
Minimum rate	0.00%
No. of agreements	4
Amount	200,000,000
Weighted average rate	3.50%
Final maturity	2,014
Fixed To Floating 150.0 Million With 3 Agreements At 3.5% [Member] \| Fixed-To-Floating [Member]
Schedule of Investments [Line Items]
Maximum rate	3.50%
Minimum rate	0.00%
No. of agreements	3
Amount	150,000,000
Weighted average rate	3.50%
Final maturity	2,015
Fixed To Floating 50.0 With 1 Agreement At 3.25% [Member] \| Fixed-To-Floating [Member]
Schedule of Investments [Line Items]
Maximum rate	3.25%
Minimum rate	0.00%
No. of agreements	1
Amount	50,000,000
Weighted average rate	3.25%
Final maturity	2,015
Floating-To-Fixed 550.0 [Member] \| Floating-To-Fixed [Member]
Schedule of Investments [Line Items]
No. of agreements	10
Amount	550,000,000
Weighted average rate	4.54%
Final maturity	2,014
Floating-To-Fixed 200.0 [Member] \| Floating-To-Fixed [Member]
Schedule of Investments [Line Items]
No. of agreements	4
Amount	$ 200,000,000
Weighted average rate	5.00%
Final maturity	2,017

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Securities Sold Under Agreements To Repurchase, Maturity Year

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- Definition

Securities Sold Under Agreements To Repurchase Weighted Average Interest Rate

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Securities Sold Under Agreement To Repurchase Interest Rate Effective Percentage Rate Range Maximum

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Securities Sold Under Agreement To Repurchase Interest Rate Effective Percentage Rate Range Minimum

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- Definition

The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount.

+ References

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 21

-Paragraph 16, 20

-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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-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 835

-SubTopic 30

-Section 55

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6584090&loc=d3e28878-108400

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The percentage points added to the reference rate to compute the variable rate on the interest rate derivative.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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