Note 5 - Financial Instruments Measured at Fair Value - Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands		Mar. 28, 2026	Dec. 27, 2025
Short-term investments		$ 277,759	$ 256,928
Corporate Debt Securities [Member]
Short-term investments	[1]	147,181	150,361
Certificates of Deposit [Member]
Short-term investments		73,196	58,156
US Treasury Securities [Member]
Short-term investments		42,033	37,652
Asset-Backed Securities [Member]
Short-term investments		14,668	10,056
Debt Security, Government, Non-US [Member]
Short-term investments		681	703
Fair Value, Recurring [Member]
Assets, Fair Value Disclosure		488,700	483,981
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Short-term investments		153,664	183,611
Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Short-term investments		73,196	58,156
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Short-term investments		42,033	37,652
Fair Value, Recurring [Member] | Asset-Backed Securities [Member]
Short-term investments		14,668	10,056
Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]
Short-term investments		681	703
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure		114,422	142,091
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Certificates of Deposit [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | US Treasury Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Asset-Backed Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Debt Security, Government, Non-US [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure		374,278	341,890
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Short-term investments		153,664	183,611
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Certificates of Deposit [Member]
Short-term investments		73,196	58,156
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
Short-term investments		42,033	37,652
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-Backed Securities [Member]
Short-term investments		14,668	10,056
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Security, Government, Non-US [Member]
Short-term investments		681	703
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Certificates of Deposit [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | US Treasury Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Asset-Backed Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Debt Security, Government, Non-US [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Cash [Member]
Cash and cash equivalents		114,422	142,091
Fair Value, Recurring [Member] | Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents		114,422	142,091
Fair Value, Recurring [Member] | Cash [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents		0	0
Fair Value, Recurring [Member] | Cash [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents		0	0
Fair Value, Recurring [Member] | Money Market Funds [Member]
Cash and cash equivalents		90,036	51,712
Fair Value, Recurring [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents		0	0
Fair Value, Recurring [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Cash and cash equivalents		90,036	51,712
Fair Value, Recurring [Member] | Money Market Funds [Member] | Fair Value, Inputs, Level 3 [Member]
Cash and cash equivalents		$ 0	$ 0

[1] Corporate debt securities include investments in financial and other corporate institutions. No single issuer represents a significant portion of the total corporate debt securities portfolio.