Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Operating activities
Net income	$ 311,183	$ 277,314	$ 275,186
Adjustments to reconcile net income to net cash provided by operating activities:
Realized (gain) loss on disposition of assets and investments	(195)	(187)	546
Stock-based compensation	127,156	104,212	95,348
Provisions for doubtful accounts and sales returns	2,870	1,025	1,572
Depreciation and amortization	46,121	40,005	35,139
Deferred income taxes	(3,090)	474	(4,293)
Changes in operating assets and liabilities, net of amounts acquired:
Accounts receivable	(40,895)	(18,867)	(20,207)
Inventories	(5,445)	(1,617)	(262)
Other current assets	(9,828)	(3,614)	(998)
Other assets	(2,502)	683	(134)
Accounts payable and accrued liabilities	18,339	16,790	9,953
Deferred revenue	105,278	83,475	103,587
Net cash provided by operating activities	548,992	499,693	495,437
Investing activities
Purchases of investments	(515,737)	(938,571)	(1,059,853)
Maturities of investments	523,983	613,927	784,601
Sales of investments	214,493	212,011	81,444
Decrease (increase) in restricted cash	59	(612)	(19)
Acquisition of intangible assets	0	0	(250)
Acquisition of businesses, net of cash acquired	(49,439)	(212,642)	(128,335)
Purchases of property and equipment	(22,718)	(26,583)	(29,867)
Net cash provided by (used in) investing activities	150,641	(352,470)	(352,279)
Financing activities
Excess tax benefit from stock-based compensation	10,283	4,091	10,371
Proceeds from the exercise of stock options and purchases of stock under employee stock purchase plan	35,299	29,591	25,174
Repurchase of common stock	(650,542)	(200,000)	(184,776)
Net cash used in financing activities	(604,960)	(166,318)	(149,231)
Net increase (decrease) in cash and cash equivalents	94,673	(19,095)	(6,073)
Effect of exchange rate changes on cash and cash equivalents	(2,864)	(2,393)	470
Cash and cash equivalents, beginning of year	189,693	211,181	216,784
Cash and cash equivalents, end of year	281,502	189,693	211,181
Supplemental information
Cash paid for taxes	$ 169,424	$ 156,833	$ 145,874