Investments & Fair Value Measurements (Tables)

6 Months Ended

12 Months Ended

Mar. 30, 2018

Sep. 29, 2017

Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]

Schedule Of Financial Assets and Liabilities Carried At Fair Value

Our cash and investment portfolio consisted of the following (in thousands):

	March 30, 2018
	Cost		Unrealized							Estimated Fair Value
			Gains		Losses			Total		Level 1		Level 2		Level 3
Cash and cash equivalents:
Cash	$	642,640						$	642,640
Cash equivalents:
Commercial paper	44,065		4		(1		)	44,068				44,068
Corporate bonds	16,398				(3		)	16,395				16,395
Money market funds	2,416		—		—			2,416		2,416
Cash and cash equivalents	705,519		4		(4		)	705,519		2,416		60,463		—
Short-term investments:
Certificate of deposit (1)	23,848		7		(5		)	23,850				23,850
U.S. agency securities	7,305				(22		)	7,283				7,283
Government bonds	535				(1		)	534		534
Commercial paper	8,575		—		(16		)	8,559				8,559
Corporate bonds	166,141		62		(578		)	165,625				165,625
Municipal debt securities	34,736		—		(90		)	34,646				34,646
Short-term investments	241,140		69		(712		)	240,497		534		239,963		—
Long-term investments:
Certificate of deposit (1)	4,845		5		—			4,850				4,850
U.S. agency securities	20,284				(324		)	19,960				19,960
Government bonds	15,356				(253		)	15,103		15,103
Corporate bonds	196,848		51		(2,473		)	194,426				194,426
Municipal debt securities	23,976				(143		)	23,833				23,833
Other long-term investments (2)	3,619		271					3,890		271
Long-term investments	264,928		327		(3,193		)	262,062		15,374		243,069		—
Total cash, cash equivalents, and investments	$	1,211,587	$	400	$	(3,909	)	$	1,208,078	$	18,324	$	543,495	$	—
Investments held in supplemental retirement plan:
Assets	3,288							3,288		3,288
Included in prepaid expenses and other current assets & other non-current assets
Liabilities	3,288							3,288		3,288
Included in accrued liabilities & other non-current liabilities

(1) Certificates of deposit include marketable securities, while those with a maturity in excess of one year as of March 30, 2018 are classified within long-term investments.

(2) Other long-term investments as of March 30, 2018 include a marketable equity security of $0.3 million, and other investments that are not carried at fair value including an equity method investment of $0.1 million and two cost method equity investments of $3.0 million and $0.5 million.

	September 29, 2017
	Cost		Unrealized							Estimated Fair Value
			Gains		Losses			Total		Level 1		Level 2		Level 3
Cash and cash equivalents:
Cash	$	623,244						$	623,244
Cash equivalents:
Commercial paper	1,223		—		—			1,223				1,223
Money market funds	2,550		—		—			2,550		2,550
Cash and cash equivalents	627,017		—		—			627,017		2,550		1,223		—
Short-term investments:
Certificate of deposit (1)	17,236		9		(1		)	17,244				17,244
U.S. agency securities	9,518		—		(20		)	9,498				9,498
Government bonds	2,034		—		(6		)	2,028		2,028
Commercial paper	15,160		2		(1		)	15,161				15,161
Corporate bonds	174,750		54		(163		)	174,641				174,641
Municipal debt securities	29,178		16		(9		)	29,185				29,185
Short-term investments	247,876		81		(200		)	247,757		2,028		245,729		—
Long-term investments:
Certificate of deposit (1)	22,940		5		(6		)	22,939				22,939
U.S. agency securities	21,779		—		(178		)	21,601				21,601
Government bonds	17,839		—		(107		)	17,732		17,732
Corporate bonds	218,857		327		(537		)	218,647				218,647
Municipal debt securities	28,913		29		(25		)	28,917				28,917
Other long-term investments (2)	4,171		357		—			4,528		357				—
Long-term investments	314,499		718		(853		)	314,364		18,089		292,104		—
Total cash, cash equivalents, and investments	$	1,189,392	$	799	$	(1,053	)	$	1,189,138	$	22,667	$	539,056	$	—
Investments held in supplemental retirement plan:
Assets	3,026							3,026		3,026
Included in prepaid expenses and other current assets & other non-current assets
Liabilities	3,026							3,026		3,026
Included in accrued liabilities & other non-current liabilities

	September 29, 2017
	Cost		Unrealized							Estimated Fair Value
			Gains		Losses			Total		Level 1		Level 2		Level 3
Cash and cash equivalents:
Cash	$	623,244						$	623,244
Cash equivalents:
Commercial paper	1,223		—		—			1,223				1,223
Money market funds	2,550		—		—			2,550		2,550
Cash and cash equivalents	627,017		—		—			627,017		2,550		1,223		—
Short-term investments:
Certificate of deposit (1)	17,236		9		(1		)	17,244				17,244
U.S. agency securities	9,518		—		(20		)	9,498				9,498
Government bonds	2,034		—		(6		)	2,028		2,028
Commercial paper	15,160		2		(1		)	15,161				15,161
Corporate bonds	174,750		54		(163		)	174,641				174,641
Municipal debt securities	29,178		16		(9		)	29,185				29,185
Short-term investments	247,876		81		(200		)	247,757		2,028		245,729		—
Long-term investments:
Certificate of deposit (1)	22,940		5		(6		)	22,939				22,939
U.S. agency securities	21,779		—		(178		)	21,601				21,601
Government bonds	17,839		—		(107		)	17,732		17,732
Corporate bonds	218,857		327		(537		)	218,647				218,647
Municipal debt securities	28,913		29		(25		)	28,917				28,917
Other long-term investments (2)	4,171		357		—			4,528		357				—
Long-term investments	314,499		718		(853		)	314,364		18,089		292,104		—
Total cash, cash equivalents, and investments	$	1,189,392	$	799	$	(1,053	)	$	1,189,138	$	22,667	$	539,056	$	—
Investments held in supplemental retirement plan:
Assets	3,026							3,026		3,026
Included in prepaid expenses and other current assets & other non-current assets
Liabilities	3,026							3,026		3,026
Included in accrued liabilities & other non-current liabilities

(1) Certificates of deposit include marketable securities, while those with a maturity in excess of one year as of September 29, 2017are classified within long-term investments.

(2) Other long-term investments as of September 29, 2017 include a marketable equity security of $0.4 million, and other investments that are not carried at fair value including an equity method investment of $0.6 million and two cost method equity investments of $3.0 million and $0.5 million.

Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value

The following table presents the gross unrealized losses and fair value for those AFS securities that were in an unrealized loss position for less than twelve months and for twelve months or greater as of March 30, 2018 and September 29, 2017 (in thousands):

	March 30, 2018										September 29, 2017
	Less Than 12 Months					12 Months Or Greater					Less Than 12 Months					12 Months Or Greater
Investment Type	Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses			Fair Value		Gross Unrealized Losses
Certificate of deposit	$	15,288	$	(5	)	$	—				$	19,750	$	(6	)	$	—	$	—
U.S. agency securities	4,704		(85		)	22,539		(261		)	19,713		(91		)	11,386		(108		)
Government bonds	13,730		(229		)	1,906		(26		)	15,029		(64		)	4,729		(49		)
Commercial paper	19,822		(16		)	—		—			4,292		(1		)	—		—
Corporate bonds	212,227		(2,070		)	106,413		(984		)	125,890		(251		)	109,806		(449		)
Municipal debt securities	56,927		(217		)	1,553		(15		)	26,749		(24		)	3,625		(10		)
Total	$	322,698	$	(2,622	)	$	132,411	$	(1,286	)	$	211,423	$	(437	)	$	129,546	$	(616	)

Available-for-sale Securities

The following table summarizes the amortized cost and estimated fair value of the AFS securities within our investment portfolio based on stated maturities as of March 30, 2018 and September 29, 2017, which are recorded within cash equivalents and both short and long-term investments in our consolidated balance sheets (in thousands):

	March 30, 2018				September 29, 2017
Range of maturity	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due within 1 year	$	304,019	$	303,376	$	251,649	$	251,530
Due in 1 to 2 years	138,508		137,073		213,555		213,154
Due in 2 to 3 years	122,802		121,099		96,773		96,682
Total	$	565,329	$	561,548	$	561,977	$	561,366