Interim Condensed Consolidated Statements Of Cash Flows - USD ($)	6 Months Ended
	Mar. 30, 2018	Mar. 31, 2017
Payments to Acquire Businesses, Net of Cash Acquired	$ 6,563,000	$ 0
Operating activities:
Net income including controlling interest	(10,713,000)	104,301,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	40,684,000	44,061,000
Stock-based compensation	36,375,000	33,198,000
Amortization of premium on investments	1,472,000	1,376,000
Provision for doubtful accounts	1,607,000	1,010,000
Deferred income taxes	48,332,000	(8,856,000)
Other non-cash items affecting net income	977,000	160,000
Changes in operating assets and liabilities:
Accounts receivable	(69,018,000)	(13,538,000)
Inventories	(352,000)	(3,253,000)
Prepaid expenses and other assets	(12,732,000)	(11,280,000)
Accounts payable and other liabilities	(38,124,000)	495,000
Income taxes, net	99,861,000	11,089,000
Deferred revenue	324,000	85,000
Other non-current liabilities	(652,000)	480,000
Net cash provided by operating activities	98,041,000	159,328,000
Investing activities:
Purchase of investments	(129,456,000)	(98,789,000)
Proceeds from sales of investment securities	64,698,000	23,071,000
Proceeds from maturities of investment securities	118,874,000	66,171,000
Purchases of property, plant and equipment	(39,734,000)	(51,230,000)
Purchases of intangible assets	(11,893,000)	(5,250,000)
Change in restricted cash	(731,000)	(2,107,000)
Net cash provided by/(used in) investing activities	(4,805,000)	(68,134,000)
Financing activities:
Proceeds from issuance of common stock	71,061,000	24,210,000
Repurchase of common stock	(34,993,000)	(50,000,000)
Payment of cash dividend	(32,956,000)	(28,494,000)
Distribution to controlling interest	(1,022,000)	(2,094,000)
Shares repurchased for tax withholdings on vesting of restricted stock	(19,946,000)	(15,799,000)
Net cash used in financing activities	(17,856,000)	(72,177,000)
Effect of foreign exchange rate changes on cash and cash equivalents	3,122,000	(2,621,000)
Net increase/(decrease) in cash and cash equivalents	78,502,000	16,396,000
Cash and cash equivalents at beginning of period	627,017,000	516,112,000
Cash and cash equivalents at end of period	705,519,000	532,508,000
Supplemental disclosure:
Cash paid for income taxes, net of refunds received	37,412,000	28,093,000
Noncash or Part Noncash Acquisition, Consideration Payable	750,000	0
Net change in PP&E purchased and unpaid at period-end	$ 1,538,000	$ 2,248,000