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Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Other Commitments [Line Items] |  |  |
Purchase Commitment for construction equipment | $ 15.0 |  |
Performance Guarantee [Member] |  |  |
Other Commitments [Line Items] |  |  |
Guarantor obligations, maximum exposure | 614.9 |  |
Guarantor Obligations Expected Costs | 324.7 |  |
Insurance Claims [Member] |  |  |
Other Commitments [Line Items] |  |  |
Insurance expense | 30.4 | $ 29.5 | $ 25.6
Contingencies Excluding Wildfire and Health Insurance [Member] |  |  |
Other Commitments [Line Items] |  |  |
Loss Contingency Insurance Policy Deductible | 1.0 |  |
Wildfire [Member] |  |  |
Other Commitments [Line Items] |  |  |
Loss Contingency Insurance Policy Deductible | 2.0 |  |
Health Insurance [Member] |  |  |
Other Commitments [Line Items] |  |  |
Loss Contingency Insurance Policy Deductible | $ 0.2 |  |

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