Note Loans (Carrying amount of Westernbank loans accounted for pursuant to ASC310-30) (Parenthetical) (Detail) $ in Millions	Dec. 31, 2015 USD ($)
Remain Subject To The Loss Sharing Agreement With FDIC \| ASC Subtopic 310-30
Accounts, Notes, Loans and Financing Receivable
Carrying amount	$ 636

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_AccountsNotesAndLoansReceivableLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration