Key economic assumptions used in measuring the servicing rights retained at the date of the residential mortgage loan securitizations and whole loan sales by the banking subsidiaries (Detail) (Residential Mortgage)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Residential Mortgage
Assumption for Fair Value as of Balance Sheet Date of Assets or Liabilities that relate to Transferor's Continuing Involvement [Line Items]
Prepayment speed	6.10%	5.60%	6.20%	7.00%
Weighted average life (in years)	0 years 0 months 5986 days	0 years 0 months 6461 days	0 years 0 months 5877 days	0 years 0 months 5183 days
Discount rate (annual rate)	10.90%	11.20%	10.80%	11.10%