Amounts Reclassified Out of Accumulated Other Comprehensive Income - Additional Information (Detail) (Accumulated Other Comprehensive Income Pre-Tax [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Accumulated Other Comprehensive Income Pre-Tax [Member]
Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified out of AOCI pre-tax basis	$ 0.1	$ 0.2