Income Taxes - Additional Information (Detail) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Income Taxes [Line Items]
Undistributed earnings of foreign subsidiaries	$ 25,200,000
Deferred tax asset	83,197,000	115,045,000
Change in deferred tax asset	31,800,000
Tax effect of gain on sale of operations	29,900,000
Effective tax rate on sale of operations	52.60%
Deferred income tax benefit		(121,800,000)
Federal and state research and development tax credit carryforwards	24,400,000
Federal and state research and development tax credit carryforwards, expiration year	2034
Net operating losses, expiration year	Sep. 30, 2030
Interest related to unrecognized benefits	300,000	200,000	200,000
Reductions from lapses in statutes of limitations	(1,236,000)	(1,022,000)	(3,732,000)
Minimum
Income Taxes [Line Items]
Anticipated unrecognized tax benefit reduction during next twelve months	1,200,000
Maximum
Income Taxes [Line Items]
Anticipated unrecognized tax benefit reduction during next twelve months	2,300,000
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	143,500,000
State
Income Taxes [Line Items]
Net operating loss carryforwards	97,900,000
Foreign
Income Taxes [Line Items]
Net operating loss carryforwards	29,500,000
Reductions from lapses in statutes of limitations	(1,200,000)
Stock Compensation Plan
Income Taxes [Line Items]
Net operating loss carryforwards	$ 11,700,000