Summary of Cash, Cash Equivalents and Marketable Securities Available for Sale (Detail) (USD $) In Thousands	Sep. 30, 2011	Sep. 30, 2010
Cash and Cash Equivalents
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	$ 135,752	$ 146,199
Fair Value	135,752	146,199
Cash and Cash Equivalents | Cash
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	68,248	63,654
Fair Value	68,248	63,654
Cash and Cash Equivalents | Money Market Funds
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	20,333	82,545
Fair Value	20,333	82,545
Cash and Cash Equivalents | Non U.S. money market funds
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	42,171
Fair Value	42,171
Cash and Cash Equivalents | Commercial Paper
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	5,000
Fair Value	5,000
Short-term marketable securities
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	105,819	68,554
Gross Unrealized Gains	14	64
Gross Unrealized Losses	(7)	(3)
Fair Value	105,826	68,615
Short-term marketable securities | Commercial Paper
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	13,997
Gross Unrealized Losses	(4)
Fair Value	13,993
Short-term marketable securities | U.S. government obligations
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	90,291	48,325
Gross Unrealized Gains	14	42
Gross Unrealized Losses	(1)
Fair Value	90,304	48,367
Short-term marketable securities | U.S. corporate debt
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	1,531	2,972
Gross Unrealized Gains		9
Gross Unrealized Losses	(2)
Fair Value	1,529	2,981
Short-term marketable securities | Non U.S. corporate debt
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost		17,257
Gross Unrealized Gains		13
Gross Unrealized Losses		(3)
Fair Value		17,267
Long-term marketable securities | Marketable Equity Securities
Cash, cash equivalents and marketable securities [Line Items]
Amortized Cost	4,649	4,847
Gross Unrealized Losses	(479)	(480)
Fair Value	$ 4,170	$ 4,367