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Multiemployer Pension Plans (Details) | 12 Months Ended
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Dec. 31, 2018 USD ($) agreements | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($)
Multiemployer Pension Plan Disclosure |  |  |
Percentage of employees participating in multiemployer pension plans to total employees | 51.00% |  |
Contributions of the Company | $ 4,700,000 | $ 4,600,000 | $ 4,700,000
Company's contributions to the multiemployer plans is less than | 5.00% |  |
USW Plan |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Employer Identification Number | 236648508 |  |
Pension Protection Act Zone Status | Green | Green |
FIP/RP Status Pending/Implemented in Current Year | No |  |
Contributions of the Company | $ 3,600,000 | $ 3,500,000 | 3,700,000
Surcharge Imposed in 2018 | No |  |
Expiration Date of Collective-Bargaining Agreement, First | Mar. 31, 2020 |  |
Expiration Date of Collective-Bargaining Agreement, Last | Feb. 28, 2021 |  |
Number of collective-bargaining agreements | agreements | 3 |  |
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Percentage of employees covered by bargaining agreement | 86.00% |  |
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities | Starting July 2015 |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Monthly contributions per hour worked by each bargaining unit employee | $ 1.50 |  |
USW Plan | Newark, Ohio and Spokane (Trentwood), Washington Facilities | Ending in July Two Thousand Nineteen |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Monthly contributions per hour worked by each bargaining unit employee | $ 1.75 |  |
USW Plan | Richmond (Bellwood), Virginia Facility |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Percentage of employees covered by bargaining agreement | 11.00% |  |
USW Plan | Florence, Alabama Facility |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Percentage of employees covered by bargaining agreement | 3.00% |  |
Other Funds |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Contributions of the Company | $ 1,100,000 | $ 1,100,000 | $ 1,000,000.0
Multiemployer Plans, Pension | Minimum |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Estimated annual contribution to pension and other postretirement benefit plans | 3,000,000.0 |  |
Multiemployer Plans, Pension | Maximum |  |  |
Multiemployer Pension Plan Disclosure |  |  |
Estimated annual contribution to pension and other postretirement benefit plans | $ 5,000,000.0 |  |

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- Definition The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation 12B -Number 240 -Section 12 -Subsection b-2 + Details
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- Definition Monthly contributions per hour worked by each bargaining unit employee. + References No definition available. + Details
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- Definition Multiemployer Plans, Collective Bargaining Arrangement, Percentage Of Employer's Participants To All Employees + References No definition available. + Details
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- Definition Percentage of contributions required by collective bargaining arrangement to all contributions required of employer for pension and other postretirement plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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- Definition Amount of contributions made to multiemployer plan by employer. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450691-114947 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (e)(1) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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- Definition Indicate the multiemployer plan's certified zone status as currently required by the Pension Protection Act of 2006 or a subsequent amendment thereof. The zone status categories are red (critical status), orange (seriously endangered), yellow (endangered), and green (none of the above). The acceptable values are "red", "orange", "yellow", "green", "other", and "NA". A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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- Definition Expiration date of the collective bargaining arrangement requiring contributions to the multiemployer plan that will expire first in a group of associated collective bargaining arrangements, in CCYY-MM-DD format. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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- Definition Expiration date of the collective bargaining arrangement requiring contributions to the multiemployer plan that will expire last in a group of associated collective bargaining arrangements, in CCYY-MM-DD format. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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- Definition Percentage of employee participants subject to a collective bargaining arrangement to all of the employer's participants in a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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- Definition Indicate whether a funding improvement plan or rehabilitation plan has been implemented or is pending for a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. The acceptable values are "no", "pending", "implemented", "other", and "NA". + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -Subparagraph (f)(1) -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
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