Reinsurance Arrangements and Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	3 Months Ended	9 Months Ended	12 Months Ended			93 Months Ended			9 Months Ended	12 Months Ended						3 Months Ended		9 Months Ended										9 Months Ended					9 Months Ended	12 Months Ended													1 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Sep. 30, 2012	Sep. 30, 2012 Contingent Consideration	Dec. 31, 2011 Contingent Consideration	Sep. 30, 2012 Non Agency Securities [Member]	Dec. 31, 2011 Non Agency Securities [Member]	Dec. 31, 2010 Non Agency Securities [Member]	Dec. 31, 2009 Non Agency Securities [Member]	Sep. 30, 2012 Agency Securities	Dec. 31, 2011 Agency Securities	Sep. 30, 2012 Ginnie Mae	Sep. 30, 2012 Mortgage Reinsurance Contracts	Sep. 30, 2011 Mortgage Reinsurance Contracts	Sep. 30, 2012 Mortgage Reinsurance Contracts	Sep. 30, 2011 Mortgage Reinsurance Contracts	Dec. 31, 2011 Mortgage Reinsurance Contracts	Sep. 30, 2012 Mortgage Reinsurance Contracts Upper Limit	Sep. 30, 2012 Standby Letters of Credit	Dec. 31, 2011 Standby Letters of Credit	Sep. 30, 2012 Mortgage Loans and Mortgage Servicing Rights	Dec. 31, 2011 Mortgage Loans and Mortgage Servicing Rights	Sep. 30, 2012 Mortgage Loans and Mortgage Servicing Rights Sales	Dec. 31, 2011 Mortgage Loans and Mortgage Servicing Rights Sales	Sep. 30, 2012 Mortgage Loans and Mortgage Servicing Rights, Repurchase Reserves	Sep. 30, 2011 Mortgage Loans and Mortgage Servicing Rights, Repurchase Reserves	Dec. 31, 2011 Mortgage Loans and Mortgage Servicing Rights, Repurchase Reserves	Sep. 30, 2012 Mortgage Loans and Mortgage Servicing Rights, Repurchase Reserves Nonperforming Financing Receivable [Member]	Dec. 31, 2011 Mortgage Loans and Mortgage Servicing Rights, Repurchase Reserves Nonperforming Financing Receivable [Member]	Sep. 30, 2012 Visa Interest	Dec. 31, 2011 Visa Interest	Dec. 31, 2010 Visa Interest	May 31, 2009 Visa Interest	Sep. 30, 2012 Tax Credit Sales [Member]	Dec. 31, 2011 Tax Credit Sales [Member]	Sep. 30, 2012 Derivative Financial Instruments, Liabilities [Member]		Dec. 31, 2011 Derivative Financial Instruments, Liabilities [Member]		Sep. 30, 2012 Not Designated as Hedging Instrument [Member] Derivative Financial Instruments, Liabilities [Member]		Dec. 31, 2011 Not Designated as Hedging Instrument [Member] Derivative Financial Instruments, Liabilities [Member]		May 31, 2009 Not Designated as Hedging Instrument [Member] Derivative Financial Instruments, Liabilities [Member] Visa Interest
Visa Share of Claims in Settlement Agreement Amount	$ 4,400,000,000	$ 4,400,000,000
Mortgage loans were covered by such mortgage reinsurance contracts																5,400,000,000		5,400,000,000		8,000,000,000
Total loss exposure ceded to the Company																187,000,000		187,000,000		309,000,000
Maximum amount of loss exposure based on funds held in each seperate trust account, including net premiums due to the trust accounts																7,000,000		7,000,000
Maximum Exposure to Loss Reserves																4,000,000		4,000,000		38,000,000
Provision For Losses, Mortgage Reinsurance																2,000,000	5,000,000	11,000,000	18,000,000
Future reported losses																					3,000,000
Future cash losses																					3,000,000
Premium income, mortgage reinsurance																2,000,000	6,000,000	10,000,000	20,000,000
Maximum potential amount obligation																						4,100,000,000	5,200,000,000														37,000,000
Fair value of contingent payments							30,000,000	10,000,000																694,000,000	320,000,000	11,000,000	8,000,000
Guarantee obligations, carrying value							30,000,000	10,000,000																694,000,000	320,000,000	11,000,000	8,000,000
Loans sold from January 1, 2005 to September 30, 2011	263,100,000,000	263,100,000,000				263,100,000,000			30,200,000,000				203,000,000,000		29,900,000,000
Loans Sold Repurchased Request Amount		1,300,000,000	1,700,000,000	1,100,000,000	1,100,000,000	6,600,000,000			15,000,000	50,000,000	55,000,000	99,000,000
Loans Sold Post 2005 Repurchased Amounts						6,400,000,000
Unpaid principal balance of loans related to unresolved requests previously received from investors	690,000,000	690,000,000	590,000,000			690,000,000			15,000,000	12,000,000			675,000,000	578,000,000
Repurchased or otherwise settled mortgages																												558,000,000	488,000,000
Repurchased mortgage loans																												246,000,000		252,000,000	92,000,000	134,000,000
Amount funded by Visa into an escrow account to fund judgments and settlements relating to litigation																																	8,200,000,000
Shares of Class B Visa Inc. common stock sold to another financial institution, shares																																															3.2
Shares of Class B Visa Inc. common stock sold to another financial institution, value					112,000,000
Shares of Class B Visa Inc. common stock sold to another financial institution, recognized a gain					112,000,000
Payments to derivative counterparty																																	25,000,000	8,000,000	17,000,000
Derivative liability positions, fair value																																	1,000,000	22,000,000					8,251,000,000	[1]	7,499,000,000	[2]	8,251,000,000	[1],[3]	7,309,000,000	[2],[3]
Common stock conversion rate																																	0.4206			0.6296
Tax Credits To Be Delivered																																					$ 3,000,000	$ 5,000,000

[1] The Company offsets cash collateral paid to and received from derivative counterparties when the derivative contracts are subject to ISDA master netting arrangements and meet the derivative offsetting requirements. The effects of offsetting on the Company's Consolidated Balance Sheets as of September 30, 2012, are presented in Note 12, "Fair Value Election and Measurement."

[2] The Company offsets cash collateral paid to and received from derivative counterparties when the derivative contracts are subject to ISDA master netting arrangements and meet the derivative offsetting requirements. The effects of offsetting on the Company's Consolidated Balance Sheets as of December 31, 2011, are presented in Note 12, "Fair Value Election and Measurement."

[3] See “Economic Hedging and Trading Activities” in this Note for further discussion.