Reconciliation of Reportable Segment Operating Income and Segment Assets to Corresponding Consolidated Amounts (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2010
Segment Reporting, Other Significant Reconciling Item [Line Items]
Other unallocated corporate expenses	$ (1,833)	[1]	$ 1,135	[1]	$ 778	[1]
Amortization of acquired intangible assets	4,618		2,411		1,969
Restructuring charges	3,275		1,036		2,529
Pension settlement	8,937
In-process research and development	3,026
Operating income (loss)	9,561		79,597		47,007
Investments in cash, cash equivalents, restricted cash and marketable securities	200,994		207,111
Long-term deferred tax assets	104,626
Investments in joint ventures	31,428		34,950
Other unallocated corporate net assets	22,463		5,890
Total assets	741,960		636,958
Operating Segments, Total
Segment Reporting, Other Significant Reconciling Item [Line Items]
Operating income (loss)	27,584		84,179		52,283
Total assets	$ 382,449		$ 389,007		$ 337,996

[1] Other unallocated corporate expenses for the year ended September 30, 2012 includes a credit of $3.3 million related to insurance proceeds received as reimbursement of litigation costs previously incurred