Income Taxes - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2013
Income Taxes [Line Items]
Effective income tax rate	37.50%	33.20%
Unrecognized tax benefits, uncertain tax positions	$ 6.3		$ 9.0
Unrecognized tax benefits, accrued interest	$ 0.4		$ 0.9