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Revenue Recognition (Tables) | 9 Months Ended
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Sep. 30, 2020
Revenue From Contract With Customer [Abstract] |
Schedule of Company's Total Revenues by Category for each Reportable Segment | The following table presents the Company’s total revenues by category for each reportable segment. Prior-year segment information has been reclassified to conform to the reportable segment change s described in Note 1.
|  | Three Months Ended |
|  | September 30, 2020 |
|  | Products and Services |  |  | Freight |  |  | Total |
|  | (Dollars in Millions) |
East Group |  | $ | 514.1 |  |  | $ | 35.2 |  |  | $ | 549.3 |
West Group |  |  | 671.4 |  |  |  | 39.8 |  |  |  | 711.2 |
Total Building Materials Business |  |  | 1,185.5 |  |  |  | 75.0 |  |  |  | 1,260.5 |
Magnesia Specialties |  |  | 55.2 |  |  |  | 5.7 |  |  |  | 60.9 |
Total |  | $ | 1,240.7 |  |  | $ | 80.7 |  |  | $ | 1,321.4 |
|  | Three Months Ended |
|  | September 30, 2019 |
|  | Products and Services |  |  | Freight |  |  | Total |
|  | (Dollars in Millions) |
East Group |  | $ | 539.8 |  |  | $ | 42.2 |  |  | $ | 582.0 |
West Group |  |  | 724.1 |  |  |  | 49.3 |  |  |  | 773.4 |
Total Building Materials Business |  |  | 1,263.9 |  |  |  | 91.5 |  |  |  | 1,355.4 |
Magnesia Specialties |  |  | 59.3 |  |  |  | 5.5 |  |  |  | 64.8 |
Total |  | $ | 1,323.2 |  |  | $ | 97.0 |  |  | $ | 1,420.2 |
|  | Nine Months Ended |
|  | September 30, 2020 |
|  | Products and Services |  |  | Freight |  |  | Total |
|  | (Dollars in Millions) |
East Group |  | $ | 1,371.8 |  |  | $ | 94.1 |  |  | $ | 1,465.9 |
West Group |  |  | 1,785.4 |  |  |  | 118.8 |  |  |  | 1,904.2 |
Total Building Materials Business |  |  | 3,157.2 |  |  |  | 212.9 |  |  |  | 3,370.1 |
Magnesia Specialties |  |  | 164.0 |  |  |  | 16.2 |  |  |  | 180.2 |
Total |  | $ | 3,321.2 |  |  | $ | 229.1 |  |  | $ | 3,550.3 |
|  | Nine Months Ended |
|  | September 30, 2019 |
|  | Products and Services |  |  | Freight |  |  | Total |
|  | (Dollars in Millions) |
East Group |  | $ | 1,398.6 |  |  | $ | 102.2 |  |  | $ | 1,500.8 |
West Group |  |  | 1,800.1 |  |  |  | 122.6 |  |  |  | 1,922.7 |
Total Building Materials Business |  |  | 3,198.7 |  |  |  | 224.8 |  |  |  | 3,423.5 |
Magnesia Specialties |  |  | 198.9 |  |  |  | 16.3 |  |  |  | 215.2 |
Total |  | $ | 3,397.6 |  |  | $ | 241.1 |  |  | $ | 3,638.7 |
Summary of Information About the Company's Contract Balances | The following table presents information about the Company’s contract balances:
(Dollars in Millions) |  | September 30, 2020 |  |  | December 31, 2019 |
Costs in excess of billings |  | $ | 8.1 |  |  | $ | 2.8 |
Billings in excess of costs |  | $ | 13.0 |  |  | $ | 7.8 |

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- Definition Tabular disclosure of contract balances and changes in contract balances. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 606 -SubTopic 10 -Section 50 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130551-203045 + Details
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