Note 5 - Financial Instruments Measured at Fair Value - Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands		Jun. 28, 2025	Dec. 28, 2024
Short-term investments		$ 44,975	$ 55,685
Corporate Debt Securities [Member]
Short-term investments	[1]	21,927	32,052
US Treasury Securities [Member]
Short-term investments		7,194	11,961
Certificates of Deposit [Member]
Short-term investments		11,592	6,972
Asset-Backed Securities [Member]
Short-term investments		3,201	3,653
Debt Security, Government, Non-US [Member]
Short-term investments		730	714
US States and Political Subdivisions Debt Securities [Member]
Short-term investments		331	333
Fair Value, Recurring [Member]
Assets, Fair Value Disclosure		209,411	262,092
Fair Value, Recurring [Member] | Corporate Debt Securities [Member]
Short-term investments		28,018	32,052
Fair Value, Recurring [Member] | US Treasury Securities [Member]
Short-term investments		7,194	11,961
Fair Value, Recurring [Member] | Certificates of Deposit [Member]
Short-term investments		11,592	6,972
Fair Value, Recurring [Member] | Asset-Backed Securities [Member]
Short-term investments		3,201	3,653
Fair Value, Recurring [Member] | Debt Security, Government, Non-US [Member]
Short-term investments		730	714
Fair Value, Recurring [Member] | US States and Political Subdivisions Debt Securities [Member]
Short-term investments		331	333
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure		121,557	136,965
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] | US Treasury 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] | 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 1 [Member] | US States and Political Subdivisions Debt Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure		87,854	125,127
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Short-term investments		28,018	32,052
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US Treasury Securities [Member]
Short-term investments		7,194	11,961
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Certificates of Deposit [Member]
Short-term investments		11,592	6,972
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Asset-Backed Securities [Member]
Short-term investments		3,201	3,653
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Debt Security, Government, Non-US [Member]
Short-term investments		730	714
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | US States and Political Subdivisions Debt Securities [Member]
Short-term investments		331	333
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] | US Treasury 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] | 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] | Fair Value, Inputs, Level 3 [Member] | US States and Political Subdivisions Debt Securities [Member]
Short-term investments		0	0
Fair Value, Recurring [Member] | Cash [Member]
Cash and cash equivalents		121,557	136,965
Fair Value, Recurring [Member] | Cash [Member] | Fair Value, Inputs, Level 1 [Member]
Cash and cash equivalents		121,557	136,965
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		36,788	69,442
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		36,788	69,442
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.