Estimated Amortization Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Expected Amortization Expense [Line Items]
Future Amortization Expense, Year One	$ 265
Future Amortization Expense, Year Two	201
Future Amortization Expense, Year Three	157
Future Amortization Expense, Year Four	123
Future Amortization Expense, Year Five	99
Mortgage Servicing Rights
Expected Amortization Expense [Line Items]
Future Amortization Expense, Year One	252
Future Amortization Expense, Year Two	193
Future Amortization Expense, Year Three	153
Future Amortization Expense, Year Four	121
Future Amortization Expense, Year Five	97
Other Intangible Assets
Expected Amortization Expense [Line Items]
Future Amortization Expense, Year One	13
Future Amortization Expense, Year Two	8
Future Amortization Expense, Year Three	4
Future Amortization Expense, Year Four	2
Future Amortization Expense, Year Five	$ 2