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Divestitures - Narrative (Details) $ in Millions | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2019 USD ($) | Jun. 30, 2019 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jul. 22, 2019 USD ($) | Jun. 03, 2019 USD ($) facility
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Number of facilities sold | facility |  |  |  |  |  |  | 2
Proceeds from sale of business, net of transaction costs |  |  | $ 158.1 | $ 0.0 | $ 0.0 |  |
Goodwill |  |  | 525.8 | 534.7 |  |  |
Gain (loss) on disposal |  |  | (1.8) | 0.0 | $ 0.0 |  |
Forged Products |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Consideration received |  |  |  |  |  |  | $ 37.0
Proceeds from sale of business, net of transaction costs |  |  | 33.0 |  |  |  |
Goodwill |  |  | (10.4) |  |  |  | $ 10.4
Gain (loss) on disposal |  | $ (7.7) | (8.1) |  |  |  |
Prior year revenue from facilities sold |  |  |  | 86.0 |  |  |
Cast Products |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Consideration received |  |  |  |  |  | $ 127.0 |
Proceeds from sale of business, net of transaction costs |  |  | 125.1 |  |  |  |
Gain (loss) on disposal | $ 6.2 |  | 6.2 |  |  |  |
Prior year revenue from facilities sold |  |  |  | $ 105.0 |  |  |
Other asset impairment charges |  |  | 10.2 |  |  |  |
Property, Plant and Equipment | Cast Products |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Other asset impairment charges |  |  | 4.5 |  |  |  |
Right of use assets, operating leases [Member] | Cast Products |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Other asset impairment charges |  |  | 1.4 |  |  |  |
Right of use assets, finance leases [Member] | Cast Products |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Other asset impairment charges |  |  | 1.0 |  |  |  |
Finite-Lived Intangible Assets [Member] | Cast Products |  |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |  |
Other asset impairment charges |  |  | $ 3.3 |  |  |  |

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