Amounts Reclassified Out of Accumulated Other Comprehensive Income - Additional Information (Detail) (Accumulated Other Comprehensive Income Pre-Tax [Member], Maximum [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income Pre-Tax [Member] | Maximum [Member]
Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified out of AOCI pre-tax basis	$ 0.1	$ 0.1