Debt instrument maturity month and year range end.

No definition available.

Name:	thrm_DebtInstrumentMaturityMonthAndYearRangeEnd
Namespace Prefix:	thrm_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument maturity month and year range start.

+ References

No definition available.

+ Details

Name:	thrm_DebtInstrumentMaturityMonthAndYearRangeStart
Namespace Prefix:	thrm_
Data Type:	xbrli:gYearMonthItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of stock interest on subsidiaries pledge to secure obligation.

+ References

No definition available.

+ Details

Name:	thrm_PercentageOfStockInterestOnSubsidiariesPledgeToSecureObligation
Namespace Prefix:	thrm_
Data Type:	num:percentItemType
Balance Type:	na
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

No definition available.

+ Details

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

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

Carrying amount of collateralized debt obligations with maturities initially due after one year or beyond the operating cycle, if longer, excluding the current portion. Obligations include, but not limited to, mortgage loans, chattel loans, and other borrowings secured by assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
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=thrm_UnitedStateTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

Debt - Additional Information (Detail)	12 Months Ended
Debt - Additional Information (Detail)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 EUR (€)
Debt Instrument [Line Items]
Maximum percentage of stock of non US subsidiaries pledge to secure obligation	66.00%	66.00%
Federal Funds Rate \| Minimum
Debt Instrument [Line Items]
Interest rate	0.20%
Federal Funds Rate \| Maximum
Debt Instrument [Line Items]
Interest rate	0.50%
Revolving Credit Facility
Debt Instrument [Line Items]
Secured long-term debt	$ 100,000,000
Line of credit facility	50,000,000
Amounts available under credit agreement	86,100,000
U.S. Term Note
Debt Instrument [Line Items]
Loan borrowing capacity	50,000,000
Amounts available under credit agreement	$ 0
Europe Term Loan
Debt Instrument [Line Items]
Loan borrowing capacity \| €		€ 20,000,000
Amounts available under credit agreement \| €		€ 0
United State Bank Of America Credit Facility
Debt Instrument [Line Items]
Interest rate	3.50%
Euro Currency Rate Loans
Debt Instrument [Line Items]
Interest rate	1.00%
Euro Currency Rate Loans \| Minimum
Debt Instrument [Line Items]
Interest rate	1.50%
Euro Currency Rate Loans \| Maximum
Debt Instrument [Line Items]
Interest rate	2.00%
Base Rate Loans \| Minimum
Debt Instrument [Line Items]
Interest rate	0.50%
Base Rate Loans \| Maximum
Debt Instrument [Line Items]
Interest rate	1.00%
DEG Loan
Debt Instrument [Line Items]
Semi-annual principal payments earliest date	2015-03
Semi-annual principal payments latest date	2019-09
DEG Vietnam Loan
Debt Instrument [Line Items]
Semi-annual principal payments earliest date	2017-11
Semi-annual principal payments latest date	2023-05