Summary of significant accounting policies (Policies)	6 Months Ended
Jun. 30, 2014
Accounting Policies [Abstract]
Use of Estimates, Policy	Use of estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the year. Actual results could differ from these estimates.
Government Grants, Policy	Government grants We record government grants when there is reasonable assurance that the grant will be received and we will comply with the conditions attached to the grants received. Grants related to income are recorded as an offset to the related expense in the accompanying statements of operations. Grants related to assets are recorded as deferred revenue and recognized on a straight-line basis over the useful life of the related asset. We continue to evaluate our compliance with the conditions attached to the related grants.
Trade and Other Accounts Receivable, Policy	Trade accounts receivable and allowance for doubtful accounts Trade accounts receivable is stated at net realizable value, which approximates fair value. Substantially all of our trade accounts receivable are due from customers in the original equipment and aftermarket automotive industries, both domestically and internationally. Trade accounts receivable includes notes receivable of $45,262,000 and $27,154,000 as of June 30, 2014 and December 31, 2013, respectively. Trade accounts receivable is reduced by an allowance for amounts that are expected to become uncollectible in the future and for disputed items. We perform periodic credit evaluations of our customers' financial condition and generally do not require collateral. We maintain allowances for doubtful customer accounts for estimated losses resulting from the inability of our customers to make required payments. The allowance for doubtful accounts is developed based on several factors including customers' credit quality, historical write-off experience and any known specific issues or disputes which exist as of the balance sheet date. If the financial condition of our customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be required.
Standard Product Warranty, Policy	Warranty We provide certain warranties relating to quality and performance of our products. An allowance for the estimated future cost of product warranties and other defective product returns is based on management's estimate of product failure rates and customer eligibility. If these factors differ from management's estimates, revisions to the estimated warranty liability may be required. The specific terms and conditions of the warranties vary depending upon the customer and the product sold.
Earnings Per Share, Policy	Earnings per share Basic earnings per share is calculated by dividing net earnings by the weighted average shares outstanding during the period. Diluted earnings per share is based on the weighted average number of shares outstanding plus the assumed issuance of common shares and related adjustment to net income attributable to common stockholders related to all potentially dilutive securities. For the three months ended June 30, 2014 and 2013, in applying the treasury stock method, equivalent shares of unvested restricted stock of 78,525 and 124,573 shares, respectively, were included in the weighted average shares outstanding in the diluted calculation. For the six months ended June 30, 2014 and 2013, in applying the treasury stock method, equivalent shares of unvested restricted stock of 124,502 and 141,498 shares, respectively, were included in the weighted average shares outstanding in the diluted calculation. Anti-dilutive stock options of 273,723 and 266,597 were excluded from the calculation of dilutive earnings per share for the three month periods ended June 30, 2014 and 2013, respectively.
Recently Adopted Accounting Standards, Policy	Recent accounting adoptions In July 2013, the FASB issued ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists to provide guidance on the presentation of unrecognized tax benefits. ASU 2013-11 requires an entity to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward with certain limited exceptions. ASU 2013-11 is effective for annual reporting periods beginning on or after December 15, 2013 and interim periods within those annual periods with earlier adoption permitted. We adopted this guidance on January 1, 2014. The adoption of this guidance did not have an impact on our consolidated financial position, results of operations or cash flows. New accounting pronouncements In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). This update provides a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. The guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts. This update is effective for annual and interim periods beginning after December 15, 2016, which will require us to adopt these provisions in the first quarter of 2017. Early application is not permitted. This update permits the use of either the retrospective or cumulative effect transition method. We are evaluating the effect this guidance will have on our consolidated financial statements and related disclosures. We have not yet selected a transition method nor have we determined the effect of the standard on our ongoing financial reporting.
Fair Value of Financial Instruments, Policy	We calculate the fair value of our interest rate swap contracts, commodity contracts and foreign currency contracts using quoted interest rate curves, quoted commodity forward rates and quoted currency forward rates. For contracts which, when aggregated by counterparty, are in a liability position, the discount rates are adjusted by the credit spread that market participants would apply if buying these contracts from our counterparties. In addition to items that are measured at fair value on a recurring basis, we also have assets and liabilities that are measured at fair value on a nonrecurring basis. As these assets and liabilities are not measured at fair value on a recurring basis, they are not included in the tables above. Assets and liabilities that are measured at fair value on a nonrecurring basis include long-lived assets (see Note 7) and certain assets acquired in business acquisitions (see Note 20). We have determined that the fair value measurements included in each of these assets and liabilities rely primarily on our assumptions as observable inputs are not available. As such, we have determined that each of these fair value measurements reside within Level 3 of the fair value hierarchy.
Derivatives, Policy	Other We present our derivative positions and any related material collateral under master netting agreements on a gross basis. We have entered into International Swaps and Derivatives Association agreements with each of its significant derivative counterparties. These agreements provide bilateral netting and offsetting of accounts that are in a liability position with those that are in an asset position. These agreements do not require us to maintain a minimum credit rating in order to be in compliance with the terms of the agreements and do not contain any margin call provisions or collateral requirements that could be triggered by derivative instruments in a net liability position. As of June 30, 2014, we have not posted any collateral to support derivatives in a liability position. For derivatives designated as cash flow hedges, changes in the time value are excluded from the assessment of hedge effectiveness. Unrealized gains and losses associated with ineffective hedges, determined using the change in fair value method, are recognized in the accompanying consolidated statements of operations. Derivative gains and losses included in AOCI for effective hedges are reclassified into the accompanying consolidated statements of operations upon recognition of the hedged transaction. Any derivative instrument designated initially, but no longer effective as a hedge, or initially not effective as a hedge, is recorded at fair value and the related gains and losses are recognized in the accompanying consolidated statements of operations. Our undesignated hedges are primarily our interest rate swaps whose fair value at inception of the instrument due to the rollover of existing interest rate swaps resulted in ineffectiveness.
Accounts Receivable Factoring Arrangements	Accounts receivable factoring arrangements We have entered into factoring agreements with various domestic and European financial institutions to sell our accounts receivable under nonrecourse agreements. These are treated as a sale. The transactions are accounted for as a reduction in accounts receivable as the agreements transfer effective control over and risk related to the receivables to the buyers. We do not service any domestic accounts after the factoring has occurred. We do not have any servicing assets or liabilities. We utilize factoring arrangements as an integral part of financing for us. The cost of factoring such accounts receivable is reflected in the accompanying consolidated statements of operations as interest expense-net with other financing costs.
Income Tax, Policy	We compute on a quarterly basis an estimated annual effective tax rate considering ordinary income and related income tax expense. Ordinary income refers to income (loss) before income tax expense excluding significant, unusual, or infrequently occurring items. The tax effect of an unusual or infrequently occurring item is recorded in the interim period in which it occurs. Other items included in income tax expense in the periods in which they occur include the cumulative effect of changes in tax laws or rates, foreign exchange gains and losses, adjustments to uncertain tax positions, and adjustments to our valuation allowance due to changes in judgment regarding the realizability of deferred tax assets in future years.
Commitments and Contingencies, Policy

Summary of significant accounting policies (Policies)

6 Months Ended

Jun. 30, 2014

Use of estimates

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expense during the year. Actual results could differ from these estimates.

Government Grants, Policy

Government grants

We record government grants when there is reasonable assurance that the grant will be received and we will comply with the conditions attached to the grants received. Grants related to income are recorded as an offset to the related expense in the accompanying statements of operations. Grants related to assets are recorded as deferred revenue and recognized on a straight-line basis over the useful life of the related asset. We continue to evaluate our compliance with the conditions attached to the related grants.

Trade and Other Accounts Receivable, Policy

Trade accounts receivable and allowance for doubtful accounts

Trade accounts receivable is stated at net realizable value, which approximates fair value. Substantially all of our trade accounts receivable are due from customers in the original equipment and aftermarket automotive industries, both domestically and internationally. Trade accounts receivable includes notes receivable of $45,262,000 and $27,154,000 as of June 30, 2014 and December 31, 2013, respectively. Trade accounts receivable is reduced by an allowance for amounts that are expected to become uncollectible in the future and for disputed items. We perform periodic credit evaluations of our customers' financial condition and generally do not require collateral. We maintain allowances for doubtful customer accounts for estimated losses resulting from the inability of our customers to make required payments. The allowance for doubtful accounts is developed based on several factors including customers' credit quality, historical write-off experience and any known specific issues or disputes which exist as of the balance sheet date. If the financial condition of our customers were to deteriorate, resulting in an impairment of their ability to make payments, additional allowances may be required.

Standard Product Warranty, Policy

Warranty

We provide certain warranties relating to quality and performance of our products. An allowance for the estimated future cost of product warranties and other defective product returns is based on management's estimate of product failure rates and customer eligibility. If these factors differ from management's estimates, revisions to the estimated warranty liability may be required. The specific terms and conditions of the warranties vary depending upon the customer and the product sold.

Earnings Per Share, Policy

Earnings per share

Basic earnings per share is calculated by dividing net earnings by the weighted average shares outstanding during the period. Diluted earnings per share is based on the weighted average number of shares outstanding plus the assumed issuance of common shares and related adjustment to net income attributable to common stockholders related to all potentially dilutive securities. For the three months ended June 30, 2014 and 2013, in applying the treasury stock method, equivalent shares of unvested restricted stock of 78,525 and 124,573 shares, respectively, were included in the weighted average shares outstanding in the diluted calculation. For the six months ended June 30, 2014 and 2013, in applying the treasury stock method, equivalent shares of unvested restricted stock of 124,502 and 141,498 shares, respectively, were included in the weighted average shares outstanding in the diluted calculation. Anti-dilutive stock options of 273,723 and 266,597 were excluded from the calculation of dilutive earnings per share for the three month periods ended June 30, 2014 and 2013, respectively.

Recently Adopted Accounting Standards, Policy

Recent accounting adoptions

In July 2013, the FASB issued ASU No. 2013-11, Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists to provide guidance on the presentation of unrecognized tax benefits. ASU 2013-11 requires an entity to present an unrecognized tax benefit, or a portion of an unrecognized tax benefit, as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward with certain limited exceptions. ASU 2013-11 is effective for annual reporting periods beginning on or after December 15, 2013 and interim periods within those annual periods with earlier adoption permitted. We adopted this guidance on January 1, 2014. The adoption of this guidance did not have an impact on our consolidated financial position, results of operations or cash flows.

New accounting pronouncements

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). This update provides a comprehensive new revenue recognition model that requires a company to recognize revenue to depict the transfer of goods or services to a customer at an amount that reflects the consideration it expects to receive in exchange for those goods or services. The guidance also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts. This update is effective for annual and interim periods beginning after December 15, 2016, which will require us to adopt these provisions in the first quarter of 2017. Early application is not permitted. This update permits the use of either the retrospective or cumulative effect transition method. We are evaluating the effect this guidance will have on our consolidated financial statements and related disclosures. We have not yet selected a transition method nor have we determined the effect of the standard on our ongoing financial reporting.

Fair Value of Financial Instruments, Policy

We calculate the fair value of our interest rate swap contracts, commodity contracts and foreign currency contracts using quoted interest rate curves, quoted commodity forward rates and quoted currency forward rates. For contracts which, when aggregated by counterparty, are in a liability position, the discount rates are adjusted by the credit spread that market participants would apply if buying these contracts from our counterparties.

In addition to items that are measured at fair value on a recurring basis, we also have assets and liabilities that are measured at fair value on a nonrecurring basis. As these assets and liabilities are not measured at fair value on a recurring basis, they are not included in the tables above. Assets and liabilities that are measured at fair value on a nonrecurring basis include long-lived assets (see Note 7) and certain assets acquired in business acquisitions (see Note 20). We have determined that the fair value measurements included in each of these assets and liabilities rely primarily on our assumptions as observable inputs are not available. As such, we have determined that each of these fair value measurements reside within Level 3 of the fair value hierarchy.

Derivatives, Policy

Other

We present our derivative positions and any related material collateral under master netting agreements on a gross basis. We have entered into International Swaps and Derivatives Association agreements with each of its significant derivative counterparties. These agreements provide bilateral netting and offsetting of accounts that are in a liability position with those that are in an asset position. These agreements do not require us to maintain a minimum credit rating in order to be in compliance with the terms of the agreements and do not contain any margin call provisions or collateral requirements that could be triggered by derivative instruments in a net liability position. As of June 30, 2014, we have not posted any collateral to support derivatives in a liability position.

For derivatives designated as cash flow hedges, changes in the time value are excluded from the assessment of hedge effectiveness. Unrealized gains and losses associated with ineffective hedges, determined using the change in fair value method, are recognized in the accompanying consolidated statements of operations. Derivative gains and losses included in AOCI for effective hedges are reclassified into the accompanying consolidated statements of operations upon recognition of the hedged transaction.

Any derivative instrument designated initially, but no longer effective as a hedge, or initially not effective as a hedge, is recorded at fair value and the related gains and losses are recognized in the accompanying consolidated statements of operations. Our undesignated hedges are primarily our interest rate swaps whose fair value at inception of the instrument due to the rollover of existing interest rate swaps resulted in ineffectiveness.

Accounts Receivable Factoring Arrangements

Accounts receivable factoring arrangements

We have entered into factoring agreements with various domestic and European financial institutions to sell our accounts receivable under nonrecourse agreements. These are treated as a sale. The transactions are accounted for as a reduction in accounts receivable as the agreements transfer effective control over and risk related to the receivables to the buyers. We do not service any domestic accounts after the factoring has occurred. We do not have any servicing assets or liabilities. We utilize factoring arrangements as an integral part of financing for us. The cost of factoring such accounts receivable is reflected in the accompanying consolidated statements of operations as interest expense-net with other financing costs.

Income Tax, Policy

We compute on a quarterly basis an estimated annual effective tax rate considering ordinary income and related income tax expense. Ordinary income refers to income (loss) before income tax expense excluding significant, unusual, or infrequently occurring items. The tax effect of an unusual or infrequently occurring item is recorded in the interim period in which it occurs. Other items included in income tax expense in the periods in which they occur include the cumulative effect of changes in tax laws or rates, foreign exchange gains and losses, adjustments to uncertain tax positions, and adjustments to our valuation allowance due to changes in judgment regarding the realizability of deferred tax assets in future years.

Commitments and Contingencies, Policy