Loans - High LTV Interest-only and Arm Loans (Detail) (USD $) In Billions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Loans Receivable, Net [Abstract]
Residential mortgage loans with high LTV and no mortgage insurance	$ 0.8	[1]	$ 0.9	[1]
Interest-only residential mortgage loans	3.8		4.0
ARM loans	$ 10.6	[2]	$ 10.4	[2]

[1] Residential mortgage loans with high LTV and no mortgage insurance includes both fixed rate and adjustable rate mortgages. Excludes $17 million and $20 million of subprime residential mortgage loans held for sale at June 30, 2013 and December 31, 2012, respectively.

[2] ARM loan balances above exclude $19 million and $19 million of subprime residential mortgage loans held for sale at June 30, 2013 and December 31, 2012, respectively. In 2013 and 2014, approximately $140 million and $304 million, respectively, of the ARM loans will experience their first interest rate reset.