Fair Value Measures (Assets and Liabilities Measured at Fair Value on Recurring Basis) (Detail) (USD $)	3 Months Ended
	Dec. 31, 2013		Sep. 30, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 40,439,538		$ 38,728,000
Document Period End Date	Dec. 31, 2013
Fair Value, Measurements, Recurring
Assets:
Money market funds	617,061,000	[1]	684,697,000	[1]
US government agency securities	1,000,000	[1]	1,000,000	[1]
Available-for-sale Securities	40,440,000		38,728,000
Foreign currency exchange contracts	949,000	[2]	2,201,000	[2]
Security price guarantees	(4,182,000)		(1,044,000)
Total assets at fair value	659,450,000		726,626,000
Liabilities:
Contingent earn-out	(1,319,000)	[3]	(450,000)	[3]
Total liabilities at fair value	(5,501,000)	[4]	(1,494,000)
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Assets:
Money market funds	617,061,000		684,697,000
US government agency securities	1,000,000		1,000,000
Available-for-sale Securities	0		0
Foreign currency exchange contracts	0		0
Security price guarantees	0		0
Total assets at fair value	618,061,000		685,697,000
Liabilities:
Contingent earn-out	0		0
Total liabilities at fair value	0	[4]	0
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets:
Money market funds	0		0
US government agency securities	0		0
Available-for-sale Securities	40,440,000		38,728,000
Foreign currency exchange contracts	949,000		2,201,000
Security price guarantees	(4,182,000)		(1,044,000)
Total assets at fair value	41,389,000		40,929,000
Liabilities:
Contingent earn-out	0		0
Total liabilities at fair value	(4,182,000)	[4]	(1,044,000)
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 3
Assets:
Money market funds	0		0
US government agency securities	0		0
Available-for-sale Securities	0		0
Foreign currency exchange contracts	0		0
Security price guarantees	0		0
Total assets at fair value	0		0
Liabilities:
Contingent earn-out	(1,319,000)		(450,000)
Total liabilities at fair value	$ (1,319,000)	[4]	$ (450,000)

[1] Money market funds and U.S. government agency securities, included in cash and cash equivalents in the accompanying balance sheets, are valued at quoted market prices in active markets.

[2] The fair values of our time deposits, marketable securities and foreign currency exchange contracts are based on the most recent observable inputs for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active or are directly or indirectly observable.

[3] The fair value of our contingent consideration arrangements are determined based on our evaluation as to the probability and amount of any earn-out that will be achieved based on expected future performance by the acquired entity.

[4] The fair values of the security price guarantees are determined using a modified Black-Scholes model, derived from observable inputs such as U.S. treasury interest rates, our common stock price, and the volatility of our common stock. The valuation model values both the put and call components of the guarantees simultaneously, with the net value of those components representing the fair value of each instrument.