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Intangible Assets - Narrative (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Goodwill [Line Items] |  |  |  |
Amortization expense | $ 24,800,000 | $ 25,900,000 | $ 8,700,000 |
Goodwill | 1,432,787,000 | 1,432,787,000 | $ 1,386,853,000 | $ 191,371,000
Non-Strategic |  |  |  |
Goodwill [Line Items] |  |  |  |
Gross goodwill | 200,000,000.0 |  |  |
Accumulated impairments | 114,100,000 |  |  |
Accumulated divestiture related write-offs | 85,900,000 |  |  |
Goodwill | $ 0 | $ 0 |  |

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