Commitments and Contingent Liabilities - Additional information (Detail)	9 Months Ended
Sep. 30, 2015
Standby Letters of Credit [Member]
Commitment And Contingencies [Line Items]
Standby letters of credit term, or less	2 years

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

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