The percent conversion premium for a convertible debt instrument.

No definition available.

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Balance Type:	na
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- Definition

The number of shares convertible per $1,000 principal amount under a convertible debt instrument.

+ References

No definition available.

+ Details

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- Definition

Percentage of quarterly installments of the original principal, with balance payable at maturity.

+ References

No definition available.

+ Details

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Namespace Prefix:	cohu_
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- Definition

The option to purchase additional principal of a debt instrument.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of available lines of credit as of the balance sheet date.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

+ References

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Period Type:	duration

- Definition

The price per share of the conversion feature embedded in the debt instrument.

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Balance Type:	na
Period Type:	instant

- Definition

Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

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Period Type:	instant

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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Balance Type:	na
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Balance Type:	na
Period Type:	instant

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Indicates type of variable interest rate on debt instrument.

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Namespace Prefix:	us-gaap_
Data Type:	enum2:enumerationSetItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the cost of borrowed funds accounted for as interest expense for debt.

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Balance Type:	credit
Period Type:	instant

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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Period Type:	instant

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt classified as current. Excludes lease obligation.

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Balance Type:	credit
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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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Note 3 - Borrowings and Credit Agreements (Details Textual) $ / shares in Units, $ in Thousands, € in Millions, ¥ in Millions, SFr in Millions, RM in Millions						1 Months Ended	12 Months Ended
	Sep. 29, 2025 USD ($) $ / shares shares	Dec. 30, 2024 MYR (RM)	Feb. 09, 2024 USD ($)	Jul. 01, 2023	Oct. 01, 2018 USD ($)	Jun. 30, 2020 EUR (€)	Dec. 27, 2025 USD ($)	Dec. 28, 2024 USD ($)	Dec. 30, 2023 USD ($)	Dec. 27, 2025 CHF (SFr)	Dec. 27, 2025 JPY (¥)	Sep. 24, 2025 $ / shares
Share Price \| $ / shares												$ 20.51
Payments for Derivative Instrument, Financing Activities							$ 31,395	$ (0)	$ (0)
Long-Term Debt							305,089
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]				Secured Overnight Financing Rate (SOFR) [Member]	London Interbank Offered Rate (LIBOR) 1 [Member]				Effective Cost of Funds (“ECOF”) [Member]
Repayments of Long-Term Debt							1,733	31,324	$ 38,788
Less: current portion							11,051	1,748
Proceeds from Lines of Credit							296,295	0	$ 0
Revolving credit facility							9,360	6,473
Lines of credit							$ 447	633
Revolving Credit Facility [Member] \| Wholly Owned Subsidiary in Malaysia [Member]
Debt Instrument, Interest Rate, Effective Percentage							4.04%			4.04%	4.04%
Debt Instrument, Basis Spread on Variable Rate		0.50%
Line of Credit Facility, Maximum Borrowing Capacity \| RM		RM 40.0
Proceeds from Lines of Credit \| RM		RM 37.9
Revolving credit facility							$ 9,400
Revolving Credit Facility [Member] \| Kita Manufacturing Co. LTD. and Kita USA, Inc. [Member]
Line of Credit Facility, Maximum Borrowing Capacity \| ¥											¥ 660
Lines of credit							400				¥ 70
Line of Credit [Member] \| Ismeca [Member]
Line of Credit Facility, Maximum Borrowing Capacity \| SFr										SFr 2
Lines of credit							$ 0	0
Number of Available Lines of Credit							1			1	1
Capped Call Transaction [Member]
Payments for Derivative Instrument, Financing Activities	$ 31,400
Convertible Senior Notes Due 2031 [Member]
Debt Instrument, Face Amount	$ 287,500
Debt Instrument, Interest Rate, Stated Percentage	1.50%
Debt Instrument, Option to Purchase Additional Principal	$ 27,500
Convertible Debt Instrument, Conversion Rate, Number of Shares Per $1,000 Principal Amount \| shares	36.7975
Debt Instrument, Convertible, Conversion Price \| $ / shares	$ 27.18
Convertible Debt Instrument, Conversion Premium, Percent	32.50%
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger	130.00%
Proceeds from Issuance of Debt	$ 278,900
Debt Instrument, Interest Rate, Effective Percentage							2.20%			2.20%	2.20%
Interest Expense, Debt							$ 1,500
Interest Expense, Debt, Excluding Amortization							1,100
Amortization of Debt Discount (Premium)							400
Debt Instrument, Unamortized Discount							9,000
Long-Term Debt							278,500
Long-Term Debt, Fair Value							321,900
Secured Term Loan Facility [Member]
Debt Instrument, Face Amount					$ 350,000
Debt Instrument, Amortization, Percentage of Principal Amount					0.25%
Debt Instrument, Basis Spread on Variable Rate				3.00%	3.00%
Repayments of Long-Term Debt			$ 29,300
Deferred Debt Issuance Cost, Writeoff			$ 200
Kita Term Loans [Member]
Long-Term Debt							1,500	1,700
Less: current portion							$ 200	200
Kita Term Loans [Member] \| Minimum [Member]
Debt Instrument, Interest Rate, Stated Percentage							0.05%			0.05%	0.05%
Kita Term Loans [Member] \| Maximum [Member]
Debt Instrument, Interest Rate, Stated Percentage							0.96%			0.96%	0.96%
Loan Facilities [Member] \| Construction Loans [Member]
Debt Instrument, Face Amount \| €						€ 10.1
Long-Term Debt							$ 6,300	6,500
Less: current portion							$ 1,100	$ 900
First Facility [Member] \| Construction Loans [Member]
Debt Instrument, Face Amount \| €						€ 3.4
Debt Instrument, Interest Rate, Stated Percentage						0.80%
Debt Instrument, Term						10 years
Second Facility [Member] \| Construction Loans [Member]
Debt Instrument, Face Amount \| €						€ 5.2
Debt Instrument, Interest Rate, Stated Percentage						1.05%
Debt Instrument, Term						15 years
Third Facility [Member] \| Construction Loans [Member]
Debt Instrument, Face Amount \| €						€ 0.9
Debt Instrument, Interest Rate, Stated Percentage						1.20%
Debt Instrument, Term						10 years