Estimated Amortization Expense (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Expected Amortization Expense [Line Items]
Future Amortization Expense, Year One	$ 149
Future Amortization Expense, Year Two	241
Future Amortization Expense, Year Three	188
Future Amortization Expense, Year Four	150
Future Amortization Expense, Year Five	121
Mortgage Servicing Rights
Expected Amortization Expense [Line Items]
Future Amortization Expense, Year One	143
Future Amortization Expense, Year Two	233
Future Amortization Expense, Year Three	184
Future Amortization Expense, Year Four	148
Future Amortization Expense, Year Five	119
Other Intangible Assets
Expected Amortization Expense [Line Items]
Future Amortization Expense, Year One	6
Future Amortization Expense, Year Two	8
Future Amortization Expense, Year Three	4
Future Amortization Expense, Year Four	2
Future Amortization Expense, Year Five	$ 2