Restructuring Expenses - Additional Information (Detail) (USD $)	12 Months Ended
	Sep. 30, 2014 position	Sep. 30, 2013 position	Sep. 30, 2012 position
Restructuring Cost and Reserve [Line Items]
Restructuring charges, net of reversals	$ 4,100,000	$ 2,500,000
Restructuring charges	4,130,000	2,719,000
Number of positions reduced	88	52	85
Reversal of severance cost	0	253,000
Employee separation
Restructuring Cost and Reserve [Line Items]
Restructuring charges	3,963,000	1,095,000	4,000,000
Reversal of severance cost	0	253,000
Facilities charges
Restructuring Cost and Reserve [Line Items]
Restructuring charges	167,000	1,624,000
Reversal of severance cost	$ 0	$ 0