Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Activities:
Net Income	$ 70,119us-gaap_ProfitLoss	$ 35,133us-gaap_ProfitLoss	$ 24,321us-gaap_ProfitLoss
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	35,029us-gaap_DepreciationAndAmortization	31,249us-gaap_DepreciationAndAmortization	30,627us-gaap_DepreciationAndAmortization
Deferred income taxes	(11,103)thrm_DeferredIncomeTaxes	(2,121)thrm_DeferredIncomeTaxes	618thrm_DeferredIncomeTaxes
(Gain) loss on revaluation of derivatives	(1,039)	(2,678)	167
Debt extinguishment expenses	1,370
Stock compensation	4,652us-gaap_ShareBasedCompensation	2,636us-gaap_ShareBasedCompensation	1,252us-gaap_ShareBasedCompensation
Loss on sale of property, plant & equipment	131	106	555
Provision for doubtful accounts	1,017us-gaap_ProvisionForDoubtfulAccounts	(705)us-gaap_ProvisionForDoubtfulAccounts	533us-gaap_ProvisionForDoubtfulAccounts
Defined benefit pension plan expense	820	(659)	50
(Gain) loss from equity investment	(785)	(436)	82
Changes in operating assets and liabilities:
Accounts receivable	(16,902)	(13,828)	(18,367)
Inventory	(8,367)us-gaap_IncreaseDecreaseInInventories	(9,600)us-gaap_IncreaseDecreaseInInventories	(5,847)us-gaap_IncreaseDecreaseInInventories
Prepaid expenses and other assets	(5,871)	(9,446)	(3,228)
Accounts payable	6,956	18,255	1,788
Accrued liabilities	4,308	11,888	4,314
Net cash provided by operating activities	80,335	59,794	36,865
Investing Activities:
Purchases of derivative financial instruments			(7,787)
Purchase of non-controlling interest		(48,567)
Investment in subsidiary, net of cash acquired	(31,474)
Loan to equity investment			(590)
Cash invested in corporate owned life insurance		(266)	(265)
Purchases of property and equipment	(38,887)	(35,861)	(26,793)
Proceeds from the sale of property and equipment	487	11	40
Net cash used in investing activities	(69,874)	(84,683)	(35,395)
Financing Activities:
Distribution paid to non-controlling interest		(3)us-gaap_PaymentsToMinorityShareholders	(290)us-gaap_PaymentsToMinorityShareholders
Cash paid for financing costs	(1,139)us-gaap_PaymentsOfFinancingCosts		(264)us-gaap_PaymentsOfFinancingCosts
Borrowing of Debt	91,592us-gaap_ProceedsFromShortTermDebt	45,669us-gaap_ProceedsFromShortTermDebt	3,326us-gaap_ProceedsFromShortTermDebt
Repayments of Debt	(79,692)us-gaap_RepaymentsOfShortTermDebt	(24,496)us-gaap_RepaymentsOfShortTermDebt	(22,953)us-gaap_RepaymentsOfShortTermDebt
Proceeds from public offering of common stock			75,532
Cash paid for the cancellation of restricted stock	(1,113)
Excess tax benefit from equity awards	1,831	2,074	171
Redemption of Series C Preferred Stock		(8,446)	(23,340)
Series C Preferred Stock Holders dividend		(696)	(2,400)
Proceeds from the exercise of Common Stock options	7,176	4,801	774
Net cash provided by financing activities	18,655	18,903	32,477
Foreign currency effect on cash and cash equivalents	1,699	2,719	366
Net (decrease) increase in cash and cash equivalents	30,815	(3,267)	34,313
Cash and cash equivalents at beginning of period	54,885	58,152	23,839
Cash and cash equivalents at end of period	85,700	54,885	58,152
Supplemental disclosure of cash flow information:
Cash paid for interest	2,558us-gaap_InterestPaidNet	2,653us-gaap_InterestPaidNet	3,545us-gaap_InterestPaidNet
Cash paid for taxes	21,756us-gaap_IncomeTaxesPaidNet	11,326us-gaap_IncomeTaxesPaidNet	8,445us-gaap_IncomeTaxesPaidNet
Supplemental disclosure of non-cash transactions:
Issuance of Common Stock to non-controlling interest		42,517	7,780
Issuance of Common Stock for Series C Preferred Stock conversion		15,108	1,031
Capital Lease		3,254us-gaap_CapitalLeaseObligationsIncurred
Common stock issued to directors and employees	2,706us-gaap_StockIssued1	1,509us-gaap_StockIssued1	429us-gaap_StockIssued1
W.E.T
Financing Activities:
Proceeds from sale of W.E.T. equity to non-controlling interest			$ 1,921

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