Marketable Securities (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 29, 2019	Mar. 30, 2019
Debt Securities, Available-for-sale [Line Items]
Gross unrealized losses	$ 109	$ 641
Amortized cost on available for sale securities held at gross unrealized loss	56,100	123,100
Securities in a continuous unrealized loss position for more than 12 months, amortized cost	49,800	120,300
Securities in a continuous unrealized loss position for more than 12 months, aggregate unrealized loss	$ 100	$ 600
Minimum
Debt Securities, Available-for-sale [Line Items]
Maturity period for highly-rated securities	1 year
Maximum
Debt Securities, Available-for-sale [Line Items]
Maturity period for highly-rated securities	3 years