v3.7.0.1

Stock-based Compensation - Additional Information (Detail) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 USD ($) Option_Holder shares | Dec. 31, 2015 USD ($) Employee shares | Dec. 31, 2014 shares | Dec. 31, 2013 shares | Dec. 31, 2012 shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Total unrecognized compensation cost related to non-vested awards | $ | $ 31.0 |  |  |  |
Converted Options [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Number of employees affected | Option_Holder | 59 |  |  |  |
Incremental compensation cost | $ | $ 0.0 |  |  |  |
Converted Options [Member] | ASP Grede Intermediate Holdings LLC [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Number of options issued |  |  | 970,395 |  |
Converted Options [Member] | ASP HHI Holdings, Inc [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Number of options issued |  |  |  | 39,885 | 1,888,450
Converted Options [Member] | ASP MD Holdings, Inc [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Number of options issued |  |  |  | 1,991,305 |
Employee Separation Agreements [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Plan modification description and terms | In accordance with these agreements, all non-vested awards vested immediately at the date of separation. In addition, the terms of the options were modified from the original term to exercise of 30 days after separation to a term of three or five years based on the respective separation agreement. |  |  |  |
Original term to exercise |  | 30 days |  |  |
Employee Separation Agreements [Member] | Restricted Stock [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Number of shares impacted by modification |  | 297,378 |  |  |
Number of employees affected | Employee |  | 5 |  |  |
Incremental compensation cost | $ |  | $ 4.1 |  |  |
Employee Separation Agreements [Member] | Employee Stock Option [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Number of shares impacted by modification |  | 1,387,087 |  |  |
Incremental compensation cost | $ |  | $ 7.6 |  |  |
Maximum [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Number of common stock permitted to be purchased by equity awards | 5,900,000 |  |  |  |
Maximum [Member] | Employee Separation Agreements [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Modified term to exercise |  | 5 years |  |  |
Minimum | Employee Separation Agreements [Member] |  |  |  |  |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] |  |  |  |  |
Modified term to exercise |  | 3 years |  |  |

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- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Description of significant modifications (such as a change in expiration dating, vesting rights, or exercise prices) to an equity-based compensation plan, including the terms of the modifications. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition An excess of the fair value of the modified award over the fair value of the award immediately before the modification. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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