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Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017 | Dec. 31, 2017
Definite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Beginning Balance |  |  |  | $ 61.0 |  |
Additions |  |  |  | 2.7 |  |
Amortization |  | $ (1.4) | $ (1.3) | (4.1) | $ (4.1) |
Ending Balance |  | 59.6 |  | 59.6 |  |
Accumulated Amortization |  | 18.9 |  | 18.9 |  | $ 14.8
Estimated Annual Amortization Expense for Definite-Lived Intangible Assets [Abstract] |  |  |  |  |  |
Remainder of 2018 |  | 1.5 |  | 1.5 |  |
2019 |  | 5.3 |  | 5.3 |  |
2020 |  | 4.9 |  | 4.9 |  |
2021 |  | 4.9 |  | 4.9 |  |
2022 |  | 4.6 |  | 4.6 |  |
Thereafter |  | 38.4 |  | 38.4 |  |
Intangible Assets [Abstract] |  |  |  |  |  |
Total Intangible Assets |  |  |  | 77.6 |  |
Total Intangible Assets - Additions |  |  |  | 2.7 |  |
Total Intangible Assets - Amortization |  | (1.4) | $ (1.3) | (4.1) | $ (4.1) |
Total Intangible Assets |  | 76.2 |  | $ 76.2 |  |
Weighted Average [Member] |  |  |  |  |  |
Definite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Remaining Useful Life (Years) |  |  |  | 18 years |  |
Trademarks and Trade Names [Member] |  |  |  |  |  |
Indefinite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Beginning Balance |  |  |  | $ 16.6 |  |
Additions |  |  |  | 0.0 |  |
Ending Balance |  | 16.6 |  | 16.6 |  |
Customer Relationships [Member] |  |  |  |  |  |
Definite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Beginning Balance |  |  |  | 54.7 |  |
Additions |  |  |  | 0.2 |  |
Amortization |  |  |  | (3.2) |  |
Ending Balance |  | 51.7 |  | $ 51.7 |  |
Remaining Useful Life (Years) |  |  |  | 19 years |  |
Intangible Assets [Abstract] |  |  |  |  |  |
Total Intangible Assets - Amortization |  |  |  | $ (3.2) |  |
Developed Technology and Other [Member] |  |  |  |  |  |
Definite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Beginning Balance | [1] |  |  | 6.3 |  |
Additions | [1] |  |  | 2.5 |  |
Amortization | [1] |  |  | (0.9) |  |
Ending Balance | [1] | $ 7.9 |  | 7.9 |  |
Intangible Assets [Abstract] |  |  |  |  |  |
Total Intangible Assets - Amortization | [1] |  |  | $ (0.9) |  |
Developed Technology and Other [Member] | Minimum [Member] |  |  |  |  |  |
Definite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Remaining Useful Life (Years) |  |  |  | 1 year |  |
Developed Technology and Other [Member] | Maximum [Member] |  |  |  |  |  |
Definite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Remaining Useful Life (Years) |  |  |  | 10 years |  |
Developed Technology and Other [Member] | Weighted Average [Member] |  |  |  |  |  |
Definite-Lived Intangible Assets [Roll Forward] |  |  |  |  |  |
Remaining Useful Life (Years) |  |  |  | 6 years |  |
[1] | Developed Technology and Other includes patents, non-compete agreements, land easements and trade names with finite lives.

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