FINANCIAL INSTRUMENTS - Schedule of Cash, Cash Equivalents, Investments and Restricted Cash and Investments Unrealized Loss Positions (Details) $ in Thousands	Sep. 29, 2019 USD ($)
Fair Value
Unrealized Losses Less than 12 Months	$ 58,997
Unrealized Losses 12 Months or Greater	38,831
Total	97,828
Gross Unrealized Loss
Unrealized Losses Less than 12 Months	(228)
Unrealized Losses 12 Months or Greater	(157)
Total	(385)
U.S. Treasury and agencies
Fair Value
Unrealized losses less than 12 months, available for sale	5,035
Unrealized losses 12 months or greater, available for sale	997
Total, available for sale	6,032
Gross Unrealized Loss
Unrealized losses less than 12 months, available for sale	(17)
Unrealized losses 12 months or greater, available for sale	(3)
Total, available for sale	(20)
Mutual funds
Fair Value
Unrealized losses less than 12 months, trading	2,974
Unrealized losses 12 months or greater, trading	7,796
Total, trading	10,770
Gross Unrealized Loss
Unrealized losses less than 12 months, trading	(174)
Unrealized losses 12 months or greater, trading	(115)
Total, trading	(289)
Government-sponsored enterprises
Fair Value
Unrealized losses less than 12 months, available for sale	0
Unrealized losses 12 months or greater, available for sale	10,973
Total, available for sale	10,973
Gross Unrealized Loss
Unrealized losses less than 12 months, available for sale	0
Unrealized losses 12 months or greater, available for sale	(23)
Total, available for sale	(23)
Foreign government bonds
Fair Value
Unrealized losses less than 12 months, available for sale	6,199
Unrealized losses 12 months or greater, available for sale	0
Total, available for sale	6,199
Gross Unrealized Loss
Unrealized losses less than 12 months, available for sale	(2)
Unrealized losses 12 months or greater, available for sale	0
Total, available for sale	(2)
Corporate notes and bonds
Fair Value
Unrealized losses less than 12 months, available for sale	40,347
Unrealized losses 12 months or greater, available for sale	19,065
Total, available for sale	59,412
Gross Unrealized Loss
Unrealized losses less than 12 months, available for sale	(29)
Unrealized losses 12 months or greater, available for sale	(16)
Total, available for sale	(45)
Mortgage backed securities — commercial
Fair Value
Unrealized losses less than 12 months, available for sale	4,442
Unrealized losses 12 months or greater, available for sale	0
Total, available for sale	4,442
Gross Unrealized Loss
Unrealized losses less than 12 months, available for sale	(6)
Unrealized losses 12 months or greater, available for sale	0
Total, available for sale	$ (6)