XML 100 R84.htm IDEA: XBRL DOCUMENT
v3.20.4

Accounting for Stock Based Compensation - Summarizes Restricted Stock Unit Activity (Detail) - shares | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Outstanding at beginning of period, Shares | 34,920 | 136,566 | 282,100
Granted, Shares | 32,406 | 19,920 | 21,681
Vested, Shares | (32,420) | (91,566) | (130,684)
Forfeited, Shares |  | (30,000) | (36,531)
Outstanding at end of period, Shares | 34,906 | 34,920 | 136,566
RSU |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Outstanding at beginning of period, Shares | 331,821 | 215,969 |
Granted, Shares | 288,798 | 220,146 | 215,969
Vested, Shares | (50,953) | (23,956) |
Forfeited, Shares | (44,927) | (80,338) |
Outstanding at end of period, Shares | 524,739 | 331,821 | 215,969
RSU | Time Vesting Shares [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Outstanding at beginning of period, Shares | 141,741 | 86,392 |
Granted, Shares | 132,864 | 107,391 | 86,392
Vested, Shares | (50,953) | (23,956) |
Forfeited, Shares | (14,747) | (28,086) |
Outstanding at end of period, Shares | 208,905 | 141,741 | 86,392
RSU | ROIC Target Shares [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Outstanding at beginning of period, Shares | 95,041 | 64,785 |
Granted, Shares | 77,967 | 56,380 | 64,785
Forfeited, Shares | (15,090) | (26,124) |
Outstanding at end of period, Shares | 157,918 | 95,041 | 64,785
RSU | TSR Target Shares [Member] |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |
Outstanding at beginning of period, Shares | 95,039 | 64,792 |
Granted, Shares | 77,967 | 56,375 | 64,792
Forfeited, Shares | (15,090) | (26,128) |
Outstanding at end of period, Shares | 157,916 | 95,039 | 64,792

X
- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(2) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_RestrictedStockUnitsRSUMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PlanNameAxis=thrm_TimeVestingSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PlanNameAxis=thrm_ROICTargetSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PlanNameAxis=thrm_TSRTargetSharesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |