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Commitments and Contingencies - Additional Information (Detail)
3 Months Ended
Mar. 31, 2020
USD ($)
Commitments and Contingencies Disclosure [Line Items]  
Letters of credit, collateral for retrospective premiums and retained losses $ 63,400,000
Commitments to purchase major equipment and investments $ 25,700,000
Agreement expire description The agreements expire in years 2020 through 2023.
Purchase obligations for remainder of 2020 $ 15,900,000
Purchase obligations for 2021 12,300,000
Purchase obligations for 2022 5,600,000
Purchase obligations for 2023 2,300,000
Current obligation 36,100,000
Letter of Credit  
Commitments and Contingencies Disclosure [Line Items]  
Amount drawn under letters of credit $ 0