Guarantees - Additional Information (Detail) $ in Thousands	Sep. 30, 2015 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations, standby letters of credit	$ 191,100
Liability related to standby letters of credit	725
Secured
Guarantor Obligations [Line Items]
Guarantor obligations, standby letters of credit	$ 129,600
Percent of secured letters of credit	67.80%