Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Income Taxes [Line Items]
Undistributed earnings of foreign subsidiaries	$ 17,500,000
Deferred income tax benefit		(121,800,000)
Federal and state research and development tax credit carryforwards	24,000,000
Federal and state research and development tax credit carryforwards, expiration year	2033
Net operating losses, expiration year	2030
Interest related to unrecognized benefits	200,000	200,000	400,000
Reductions from lapses in statutes of limitations	(1,022,000)	(3,732,000)	(961,000)
Anticipated unrecognized tax benefit reduction during next twelve months	1,300,000
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	242,000,000
State
Income Taxes [Line Items]
Net operating loss carryforwards	122,200,000
Foreign
Income Taxes [Line Items]
Net operating loss carryforwards	37,300,000
Reductions from lapses in statutes of limitations	(1,000,000)
Stock Compensation Plan
Income Taxes [Line Items]
Net operating loss carryforwards	$ 11,700,000