Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income (loss)	$ 13,877	$ (9,141)
Adjustments to reconcile net income (loss) to net cash provided (used) by operating activities:
Depreciation and amortization	21,046	21,454
Stock-based compensation	18,331	17,988
Non-cash portion of restructuring charges	0	260
Other non-cash items, net	361	330
Changes in operating assets and liabilities, excluding the effects of acquisitions:
Accounts receivable	21,603	21,184
Accounts payable and accrued expenses	(12,885)	232
Accrued compensation and benefits	(40,172)	(53,840)
Deferred revenue	22,055	(11,726)
Accrued income taxes	(14,272)	(6,096)
Other current assets and prepaid expenses	(8,963)	(15,229)
Other noncurrent assets and liabilities	4,146	(13,292)
Net cash provided (used) by operating activities	25,127	(47,876)
Cash flows from investing activities:
Additions to property and equipment	(6,377)	(7,100)
Payments to Acquire Intangible Assets	2,500	0
Purchases of short- and long-term marketable securities	(4,248)	0
Proceeds from maturities of short- and long-term marketable securities	3,740	0
Proceeds from sales of investments	0	1,502
Net cash used in investing activities	(9,385)	(5,598)
Cash flows from financing activities:
Borrowings under credit facility and senior notes	50,000	60,000
Repayments of borrowings under credit facility	(20,000)	(80,000)
Contingent consideration	(3,176)	(2,711)
Payments of withholding taxes in connection with vesting of stock-based awards	(33,488)	(18,623)
Net cash used in financing activities	(6,664)	(41,334)
Effect of exchange rate changes on cash and cash equivalents	2,598	(9,760)
Net increase (decrease) in cash and cash equivalents	11,676	(104,568)
Cash and cash equivalents, beginning of period	280,003	277,935
Cash and cash equivalents, end of period	$ 291,679	$ 173,367