Medium- And Long-Term Debt (Schedule Of Medium- And Long-Term Debt) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
Jun. 30, 2013	Dec. 31, 2012
Debt Instruments [Line Items]
Total medium- and long-term debt	$ 3,601	$ 4,720
Parent Company
Debt Instruments [Line Items]
Total medium- and long-term debt	622	629
Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	1,951	2,058
Total medium- and long-term debt	2,979	4,091
4.80% subordinated notes due 2015 [Member] \| Parent Company
Debt Instruments [Line Items]
Subordinated notes	323	330
Fixed Interest Rate	4.80%	4.80%
Maturity Date	May 01, 2015	May 01, 2015
3.00% notes due 2015 [Member] \| Parent Company
Debt Instruments [Line Items]
Medium-term notes	299	299
Fixed Interest Rate	3.00%	3.00%
Maturity Date	Sep. 16, 2015	Sep. 16, 2015
7.375% subordinated notes due 2013 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	0	51
Fixed Interest Rate	7.375%	7.375%
Maturity Date	Apr. 15, 2013	Apr. 15, 2013
5.70% subordinated notes due 2014 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	261	267
Fixed Interest Rate	5.70%	5.70%
Maturity Date	Jun. 01, 2014	Jun. 01, 2014
5.75% subordinated notes due 2016 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	686	694
Fixed Interest Rate	5.75%	5.75%
Maturity Date	Nov. 21, 2016	Nov. 21, 2016
5.20% subordinated notes due 2017 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	572	593
Fixed Interest Rate	5.20%	5.20%
Maturity Date	Aug. 22, 2017	Aug. 22, 2017
Floating-rate based on LIBOR index subordinated notes due 2018 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	26	26
Maturity Date	Sep. 15, 2018	Sep. 15, 2018
8.375% subordinated notes due 2024 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	185	186
Fixed Interest Rate	8.375%	8.375%
Maturity Date	Jul. 15, 2024	Jul. 15, 2024
7.875% subordinated notes due 2026 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Subordinated notes	221	241
Fixed Interest Rate	7.875%	7.875%
Maturity Date	Sep. 15, 2026	Sep. 15, 2026
Federal Home Loan Bank advances floating-rate based on LIBOR indices due 2013 to 2014 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Federal Home Loan Bank advances	1,000	2,000
Maturity Date Range - start	May 07, 2013	May 07, 2013
Maturity Date Range - end	May 07, 2014	May 07, 2014
6.0% - 6.4% fixed-rate notes due 2020 [Member] \| Subsidiaries
Debt Instruments [Line Items]
Other Notes	$ 28	$ 33
Floating Interest Rate - minimum	6.00%	6.00%
Floating Interest Rate - maximum	6.40%	6.40%
Maturity Date	Jun. 30, 2020	Jun. 30, 2020

Interest rate stated in the contractual debt agreement.

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When presenting a range of interest rates, the highest stated (contractual) rate for funds borrowed under the debt agreement as of the balance sheet date.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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-Publisher SEC

-Name Regulation S-X (SX)

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Including both current and noncurrent portions, Federal Home Loan Bank borrowings initially due beyond one year or beyond the normal operating cycle if longer.

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-Name Accounting Standards Codification

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-Number Title 12

-Section 563c.102

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Carrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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-Name Staff Accounting Bulletin (SAB)

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-Number 210

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-Subsection 19, 20, 22

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