Portion of Loan Included In Current Liabilities

No definition available.

Name:	ctkb_PortionOfLoanIncludedInCurrentLiabilities
Namespace Prefix:	ctkb_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 835
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482925/835-30-45-2

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(a)(1))
-Publisher FASB
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-URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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

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

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
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-Section S99
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-Publisher FASB
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+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(f))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

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-Topic 470
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+ Details

Name:	us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

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-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

+ Details

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

- Definition

Amount of cash inflow from contractual arrangement with the lender, including but not limited to, letter of credit, standby letter of credit and revolving credit arrangements.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

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-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

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-URI https://asc.fasb.org/1943274/2147482740/230-10-45-14

+ Details

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

- Details

Name:	us-gaap_DebtInstrumentAxis=ctkb_WuxiLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctkb_BankOfChinaMaximumCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctkb_BankOfChinaMaximumCreditRenewalAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctkb_BankOfNingboMaximumCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ctkb_BankOfCommunicationChinaLoanAgreementMember
Namespace Prefix:
Data Type:	na
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Period Type:

Debt (Details) $ in Thousands, ¥ in Millions		1 Months Ended					3 Months Ended				9 Months Ended
Debt (Details) $ in Thousands, ¥ in Millions	Jun. 11, 2025 USD ($)	Mar. 31, 2025 USD ($)	Mar. 31, 2025 CNY (¥)	Jan. 31, 2025 USD ($)	Jan. 31, 2025 CNY (¥)	Apr. 30, 2023 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2025 CNY (¥)	Dec. 31, 2024 USD ($)	Dec. 31, 2024 CNY (¥)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 CNY (¥)	Jun. 11, 2025 CNY (¥)	Jan. 06, 2025 USD ($)	Jan. 06, 2025 CNY (¥)	Oct. 24, 2024 USD ($)	Oct. 24, 2024 CNY (¥)
Line of Credit Facility [Line Items]
Proceeds from lines of credit											$ 4,166	$ 1,396
Wuxi Loan
Line of Credit Facility [Line Items]
Loan amount						$ 2,900	$ 1,200				$ 1,200
Debt instrument term (in years)						5 years					5 years
Portion of loan included in current liabilities							$ 600				$ 600
Interest rate on loan (as percent)							3.80%				3.80%		3.80%
Debt instrument, basis spread on variable rate (as percent)											0.20%
Bank of China Maximum Credit Agreement \| Revolving Credit Facility \| Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity																	$ 5,200	¥ 37.0
Bank Of China Maximum Credit Renewal Agreement \| Revolving Credit Facility \| Line of Credit
Line of Credit Facility [Line Items]
Proceeds from lines of credit							$ 2,100	¥ 15.0	$ 2,800	¥ 20.0
Long-term line of credit							300				$ 300		¥ 2.0
Bank of Ningbo Maximum Credit Agreement \| Revolving Credit Facility \| Line of Credit
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity															$ 1,400	¥ 10.0
Proceeds from lines of credit		$ 450	¥ 3.0	$ 300	¥ 2.0
Long-term line of credit							$ 750				$ 750		¥ 5.0
Interest rate (as percent)		2.55%	2.55%	3.10%	3.10%
Bank Of Communication, China, Loan Agreement \| Revolving Credit Facility \| Line of Credit
Line of Credit Facility [Line Items]
Debt instrument term (in years)	1 year
Line of credit facility, maximum borrowing capacity	$ 1,400													¥ 10.0
Interest rate (as percent)	2.80%													2.80%