Note 5 - Financial Instruments Measured at Fair Value - Short-term Investments by Security Type (Details) - USD ($) $ in Thousands		Dec. 30, 2023	Dec. 31, 2022
Amortized cost		$ 90,100	$ 143,952
Gross unrealized gains		215	61
Gross unrealized losses	[1]	141	778
Short-term investments		90,174	143,235
Estimated fair value		90,174	143,235
Corporate Debt Securities [Member]
Amortized cost	[2]	45,105	59,283
Gross unrealized gains	[2]	147	30
Gross unrealized losses	[1],[2]	15	240
Short-term investments	[2]	45,237	59,073
Estimated fair value	[2]	45,237	59,073
US Treasury Securities [Member]
Amortized cost		20,439	34,614
Gross unrealized gains		26	1
Gross unrealized losses	[1]	116	418
Short-term investments		20,349	34,197
Estimated fair value		20,349	34,197
Certificates of Deposit [Member]
Amortized cost		15,468	36,500
Gross unrealized gains		20	20
Gross unrealized losses	[1]	0	41
Short-term investments		15,488	36,479
Estimated fair value		15,488	36,479
Asset-Backed Securities [Member]
Amortized cost		8,017	12,727
Gross unrealized gains		17	10
Gross unrealized losses		10	79
Short-term investments		8,024	12,658
Estimated fair value		8,024	12,658
Debt Security, Government, Non-US [Member]
Amortized cost		741	828
Gross unrealized gains		0	0
Gross unrealized losses	[1]	0	0
Short-term investments		741	828
Estimated fair value		741	$ 828
US States and Political Subdivisions Debt Securities [Member]
Amortized cost		330
Gross unrealized gains		5
Gross unrealized losses		0
Short-term investments		335
Estimated fair value		$ 335

[1] As of December 30, 2023, the cost and fair value of investments with loss positions were approximately $38.5 million and $38.4 million, respectively. As of December 31, 2022, the cost and fair value of investments with loss positions was approximately $86.3 million and $85.5 million, respectively. We evaluated the nature of these investments, credit worthiness of the issuer and the duration of these impairments to determine if an other-than-temporary decline in fair value had occurred and concluded that these losses were temporary and we have the ability and intent to hold these investments to maturity.

[2] 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.