Loans - Schedule of Aging of Non-Covered Loans (Parenthetical) (Detail)	12 Months Ended
Dec. 31, 2014
Receivables [Abstract]
Past due loans threshold period	90 days

Threshold period past due for financing receivable to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_ThresholdPeriodPastDueForWriteoffOfFinancingReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration