Reinsurance Arrangements and Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended		12 Months Ended				99 Months Ended			99 Months Ended	3 Months Ended	12 Months Ended			99 Months Ended			3 Months Ended									3 Months Ended						1 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Mar. 31, 2013	Mar. 31, 2013 Contingent Consideration	Dec. 31, 2012 Contingent Consideration	Mar. 31, 2013 Ginnie Mae	Mar. 31, 2013 Non Government Sponsored Agency [Member]	Dec. 31, 2012 Non Government Sponsored Agency [Member]	Dec. 31, 2011 Non Government Sponsored Agency [Member]	Dec. 31, 2010 Non Government Sponsored Agency [Member]	Mar. 31, 2013 Non Government Sponsored Agency [Member]	Mar. 31, 2013 US Government Sponsored Agency [Member]	Dec. 31, 2012 US Government Sponsored Agency [Member]	Mar. 31, 2013 Mortgage Reinsurance Contracts	Mar. 31, 2012 Mortgage Reinsurance Contracts	Dec. 31, 2012 Mortgage Reinsurance Contracts	Mar. 31, 2013 Mortgage Reinsurance Contracts Upper Limit	Dec. 31, 2012 Mortgage Reinsurance Contracts Upper Limit	Mar. 31, 2013 Standby Letters of Credit	Dec. 31, 2012 Standby Letters of Credit	Mar. 31, 2013 Mortgage Servicing Rights [Member]	Dec. 31, 2012 Mortgage Servicing Rights [Member]	Mar. 31, 2013 Visa Interest	Mar. 31, 2012 Visa Interest	Dec. 31, 2012 Visa Interest	May 31, 2009 Visa Interest	Mar. 31, 2013 Tax Credit Sales [Member]	Dec. 31, 2012 Tax Credit Sales [Member]	May 31, 2009 Not Designated as Hedging Instrument [Member] Derivative Financial Instruments, Liabilities [Member] Visa Interest	Mar. 31, 2013 Loans Held For Investment [Member]	Dec. 31, 2012 Loans Held For Investment [Member]	Mar. 31, 2013 Loans Held For Investment [Member] Nonperforming Financing Receivable [Member]	Dec. 31, 2012 Loans Held For Investment [Member] Nonperforming Financing Receivable [Member]	Mar. 31, 2013 Residential Mortgage, Loans Held For Sale [Member]	Dec. 31, 2012 Residential Mortgage, Loans Held For Sale [Member]	Mar. 31, 2013 Residential Mortgage, Loans Held For Sale [Member] Nonperforming Financing Receivable [Member]	Dec. 31, 2012 Residential Mortgage, Loans Held For Sale [Member] Nonperforming Financing Receivable [Member]
Mortgage loans were covered by such mortgage reinsurance contracts																		$ 1,900,000,000		$ 5,200,000,000
Total loss exposure ceded to the Company																		97,000,000		179,000,000
Maximum amount of loss exposure based on funds held in each seperate trust account, including net premiums due to the trust accounts																		6,000,000		6,000,000
Valuation Allowances and Reserves, Balance																		3,000,000		3,000,000
Future reported losses																					3,000,000	3,000,000
Future cash losses																					3,000,000
Premium income, mortgage reinsurance																		1,000,000	5,000,000
Provision For Losses, Mortgage Reinsurance																		1,000,000	6,000,000
Maximum potential amount obligation																							3,900,000,000	4,000,000,000							37,000,000
Loans sold from January 1, 2005 to September 30, 2011							278,300,000,000			32,000,000,000					30,300,000,000	216,000,000,000
Loans Sold Repurchased Request Amount	491,000,000		1,700,000,000	1,700,000,000	1,100,000,000		7,600,000,000				3,000,000	22,000,000	50,000,000	55,000,000
Unpaid principal balance of loans related to unresolved requests previously received from investors	559,000,000		655,000,000				559,000,000				6,000,000	16,000,000			6,000,000	553,000,000	639,000,000
Reserve For Mortgage Loan Repurchase Losses	513,000,000	383,000,000	632,000,000	320,000,000			513,000,000
Repurchased or otherwise settled mortgages	249,000,000	194,000,000
Repurchased mortgage loans	295,000,000		240,000,000				295,000,000																											257,000,000	209,000,000	54,000,000	70,000,000	38,000,000	31,000,000	38,000,000	31,000,000
Loss Contingency Accrual, at Carrying Value								30,000,000	30,000,000																12,000,000	12,000,000
Third Party Escrow, Gross Funded Since Inception																											8,500,000,000
Third Party Escrow, Amount Paid From Escrow																											4,100,000,000
Third Party litigation claims paid from escrow																											4,400,000,000
Number Of Shares Sold To Selected Financial Institutions																																	3.2
Shares of Class B Visa Inc Common Stock Sold to Another FinancialIinstitution, Value						112,000,000
Gain (Loss) on Sale of Other Investments						112,000,000
Common stock conversion rate																													0.4206	0.6296
Payments to derivative counterparty																											1,000,000	22,000,000
Visa Share of Claims in Settlement Agreement Amount																											4,400,000,000
Tax Credits To Be Delivered																															$ 2,000,000	$ 3,000,000