Financial Instruments - Gross Unrealized Losses and Fair Values (Details) - USD ($) $ in Thousands	May 03, 2020	Apr. 30, 2019
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Fair Value, Less than 12 months	$ 94,074	$ 14,689
Unrealized Loss, Less than 12 Months	(509)	(4)
Fair Value, Greater than 12 months	0	1,000
Unrealized Loss, Greater than 12 months	0	0
Fair Value, Total	94,074	15,689
Unrealized Loss, Total	(509)	(4)
U.S. government treasury notes
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Fair Value, Less than 12 months	14,975	0
Unrealized Loss, Less than 12 Months	(1)	0
Fair Value, Greater than 12 months	0	1,000
Unrealized Loss, Greater than 12 months	0	0
Fair Value, Total	14,975	1,000
Unrealized Loss, Total	(1)	0
U.S. government agencies
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Fair Value, Less than 12 months	6,984	4,998
Unrealized Loss, Less than 12 Months	(11)	(3)
Fair Value, Greater than 12 months	0	0
Unrealized Loss, Greater than 12 months	0	0
Fair Value, Total	6,984	4,998
Unrealized Loss, Total	(11)	(3)
Corporate debt securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Fair Value, Less than 12 months	57,571	9,691
Unrealized Loss, Less than 12 Months	(412)	(1)
Fair Value, Greater than 12 months	0	0
Unrealized Loss, Greater than 12 months	0	0
Fair Value, Total	57,571	9,691
Unrealized Loss, Total	(412)	$ (1)
Asset-backed securities
Debt Securities, Available-for-sale, Unrealized Loss Position, Accumulated Loss [Abstract]
Fair Value, Less than 12 months	14,544
Unrealized Loss, Less than 12 Months	(85)
Fair Value, Greater than 12 months	0
Unrealized Loss, Greater than 12 months	0
Fair Value, Total	14,544
Unrealized Loss, Total	$ (85)

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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