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v3.20.4

Summary of Significant Accounting Policies (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2020
Cash Equivalents and Short-term Investments [Abstract] |  |  |
Short-term investments | $ 4.1 | $ 1.6 | $ 4.1
Unrealized holding gains and losses on short-term bank investments |  |  | $ 0.0
Trade Accounts Receivable [Abstract] |  |  |
Past due threshold for individual collectability review |  |  | 90 days
Allowance for doubtful accounts | 15.0 | 12.9 | $ 15.0
Property, Plant and Equipment [Abstract] |  |  |
Initial term of long term evergreen contracts |  |  | 10 years
Investment in Joint Ventures [Abstract] |  |  |
Equity method investment | 17.0 | 16.1 | $ 17.0
Revenue Recognition [Abstract] |  |  |
Revenue adjustments | $ 0.0 | $ 0.0 |
Buildings [Member] | Minimum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 3.00%
Buildings [Member] | Maximum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 6.67%
Machinery and Equipment [Member] | Minimum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 6.67%
Machinery and Equipment [Member] | Maximum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 12.50%
Furniture and Fixtures [Member] | Minimum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 8.00%
Furniture and Fixtures [Member] | Maximum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 12.50%
Computer Equipment and Software-related Assets [Member] | Minimum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 12.50%
Computer Equipment and Software-related Assets [Member] | Maximum [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Annual rates of depreciation |  |  | 25.00%
PCC Production Facilities [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Estimated useful life |  |  | 15 years
Machinery and Equipment for Natural Stone Mining and Processing Plants and Chemical Plants [Member] |  |  |
Property, Plant and Equipment [Abstract] |  |  |
Estimated useful life |  |  | 15 years

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- Definition Estimate-to-actual adjustment to revenue for shipments sold to customers under PCC contracts. During the year, the price per ton billed to customers is based on periodic estimates of the total annual volume that will be sold to the customer. Revenues are adjusted at the end of each year to reflect the actual volume sold. + References No definition available. + Details
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- Definition The initial length of time that the company's long-term evergreen contracts in effect. Sales of PCC (precipitated calcium carbonate) are predominantly pursuant to long-term evergreen contracts, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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