Supplemental Disclosure for Earnings Per Common Share (Additional Information) (Detail)	9 Months Ended
Jun. 30, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	51,295

Gross number of share options (or share units) granted during the period.

No definition available.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration