Stock-Based Compensation Plans - Schedule of Stock Option Activity (Detail) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Number of Shares Outstanding, Beginning balance	1,368,984	1,325,438	1,515,188
Number of Shares, Granted	138,837	178,924	299,832
Number of Shares, Exercised	(190,434)	(10,273)	(11,379)
Number of Shares, Forfeited	(106,768)	(125,105)	(478,203)
Number of Shares Outstanding, Ending balance	1,210,619	1,368,984	1,325,438
Weighted Average Exercise Price, Beginning Balance	$ 20.13	$ 21.25	$ 25.59
Number of Shares, Exercisable	845,089
Weighted Average Exercise Price, Granted	$ 22.71	$ 20.85	$ 12.46
Weighted Average Exercise Price, Exercised	$ 14.42	$ 14.40	$ 10.03
Weighted Average Exercise Price, Forfeited	$ 31.26	$ 33.47	$ 29.76
Weighted Average Exercise Price, Ending balance	$ 20.35	$ 20.13	$ 21.25
Weighted Average Exercise Price, Exercisable	$ 21.48