Long-Term Debt - Additional Information (Detail) (USD $)																12 Months Ended			12 Months Ended			12 Months Ended		12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended			12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2012 Parent company	Dec. 31, 2011 Parent company	Dec. 31, 2011 Parent company Senior Debt Obligations Fixed Rate 3.625 Percent Notes Due 2016	Dec. 31, 2012 Parent company Senior Debt Obligations Fixed Rate 6.25 Percent Notes Due 2013	Dec. 31, 2011 Parent company Senior Debt Obligations Fixed Rate 6.25 Percent Notes Due 2013	Dec. 31, 2008 Parent company Senior Debt Obligations Fixed Rate 6.25 Percent Notes Due 2013	Dec. 31, 2012 Parent company Senior Debt Obligations Fixed Rate 3.50 Percent Notes Due 2022	Dec. 31, 2012 Parent company Subordinated debt Floating Rate 0.98 Percent Notes Due 2016	Dec. 31, 2011 Parent company Subordinated debt Floating Rate 0.98 Percent Notes Due 2016	Dec. 31, 2012 Parent company Subordinated debt Fixed Rate 5.45 Percent Notes Due 2017	Dec. 31, 2011 Parent company Subordinated debt Fixed Rate 5.45 Percent Notes Due 2017	Dec. 31, 2012 Parent company Subordinated debt Fixed Rate 5.45 Percent Notes Due 2017 Three Month L I B O R [Member]	Dec. 31, 2012 Parent company Subordinated debt Fixed Rate 4.50 Percent Notes Due 2018	Dec. 31, 2011 Parent company Subordinated debt Fixed Rate 4.50 Percent Notes Due 2018	Dec. 31, 2012 Parent company Subordinated debt Fixed Rate 4.50 Percent Notes Due 2018 Three Month L I B O R [Member]	Dec. 31, 2012 Parent company Subordinated debt Fixed Rate 8.25 Percent Notes Due 2038	Dec. 31, 2011 Parent company Subordinated debt Fixed Rate 8.25 Percent Notes Due 2038	Dec. 31, 2012 Parent company Junior subordinated debt Fixed Rate 7.25 Percent Notes Due 2067 Group 1 [Member]	Dec. 31, 2011 Parent company Junior subordinated debt Fixed Rate 7.25 Percent Notes Due 2067 Group 1 [Member]	Dec. 31, 2012 Parent company Junior subordinated debt Fixed Rate 7.25 Percent Notes Due 2067 Group 2 [Member]	Dec. 31, 2011 Parent company Junior subordinated debt Fixed Rate 7.25 Percent Notes Due 2067 Group 2 [Member]	Dec. 31, 2012 Parent company Junior subordinated debt Fixed Rate 6.50 Percent Notes Due 2067	Dec. 31, 2011 Parent company Junior subordinated debt Fixed Rate 6.50 Percent Notes Due 2067	Dec. 31, 2012 Parent company Junior subordinated debt Fixed Rate 6.50 Percent Notes Due 2067 Three Month L I B O R [Member]	Dec. 31, 2012 Parent company Junior subordinated debt Fixed Rate 6.50 Percent Notes Due 2067 One Month L I B O R [Member]	Dec. 31, 2012 Parent company Structured Repurchase Agreements	Dec. 31, 2012 Subsidiaries	Dec. 31, 2012 Subsidiaries Federal Home Loan Bank Advances 0.05 To 8.34 Percent Due 2014 Through 2037	Dec. 31, 2011 Subsidiaries Federal Home Loan Bank Advances 0.05 To 8.34 Percent Due 2014 Through 2037	Dec. 31, 2012 Subsidiaries Senior Debt Obligations Floating Rate Bank Notes Due 2013	Dec. 31, 2011 Subsidiaries Senior Debt Obligations Floating Rate Bank Notes Due 2013	Dec. 31, 2012 Subsidiaries Senior Debt Obligations Floating Rate Bank Notes Due 2013 Three Month L I B O R [Member]	Dec. 31, 2012 Subsidiaries Subordinated debt Fixed Rate 4.75 Percent Bank Notes Due 2015	Dec. 31, 2011 Subsidiaries Subordinated debt Fixed Rate 4.75 Percent Bank Notes Due 2015	Dec. 31, 2012 Subsidiaries Junior subordinated debt Floating Rate 2.24 Percent Debentures Due 2035	Dec. 31, 2012 Subsidiaries Junior subordinated debt Floating Rate 2.24 Percent Debentures Due 2035 Three Month L I B O R [Member] Group 2 [Member]
Debt Instrument [Line Items]
Issue of senior notes to third party investors							$ 1,000,000,000			$ 750,000,000	$ 500,000,000									$ 1,000,000,000
Debt Instrument Principal Amount Redeemed																						575,000,000		862,500,000
Gain on the extinguishment																						17,000,000		9,000,000
Extinguishment of Debt, Amount																														375,000,000		1,000,000,000
Payments of Debt Extinguishment Costs																														9,000,000		134,000,000
Debt, available for future issuance																															19,000,000,000
Debt, discounts and premiums	20,000,000		18,000,000
Additions for mark-to-market adjustments on hedged debt	555,000,000		662,000,000
Amount of debt converted to floating rate								675,000,000												705,000,000
Interest rate paid								2.72%	2.84%					0.76%			0.56%			3.36%												4.56%					0.41%
Basis points																42			25									137	237							11			169	142
Interest Rate Maximum																																8.34%
Interest Rate Minimum																																0.05%
Federa lHome Loan Bank Advances General Debt Obligations Disclosures Collateral Pledged1																																19,100,000,000
FHLB advance																																53,000,000
FHLB advances maturing 2014																																3,000,000
FHLB advances maturing 2015																																4,000,000
FHLB advances maturing 2016																																4,000,000
FHLB advances maturing thereafter																																42,000,000
Long-term debt	7,085,000,000	[1]	9,682,000,000	[1]	5,751,000,000	6,784,000,000		758,000,000	779,000,000			250,000,000	250,000,000	583,000,000	589,000,000		584,000,000	581,000,000		1,330,000,000	1,348,000,000		594,000,000		894,000,000	750,000,000	750,000,000							500,000,000	500,000,000		546,000,000	561,000,000
Debt, outstanding principal balance	$ 6,500,000,000		$ 9,000,000,000																														$ 1,000,000,000
Redemption price, per share																						$ 25		$ 25
Unpaid or accrued distribution factor through the actual redemption date																						$ 0.453125		$ 0.422917

[1] At December 31, 2012 and 2011, includes $0 and $30 of cash, $0 and $7 of other short-term investments, $50 and $50 of commercial mortgage loans, $0 and $223 of home equity loans, $0 and $259 of automobile loans, ($5) and ($10) of ALLL, $3 and $4 of other assets, $0 and $4 of other liabilities, $0 and $191 of long-term debt from consolidated VIEs that are included in their respective captions. See Note 10.