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Costs and Estimated Earnings on Uncompleted Contracts | 12 Months Ended
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Dec. 31, 2017
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Costs and Estimated Earnings on Uncompleted Contracts | 8. Costs and Estimated Earnings on Uncompleted Contracts Costs and estimated earnings on uncompleted contracts consist of (in millions):
|  | December 31, |
|  | 2017 |  |  | 2016 |
Costs incurred on uncompleted contracts |  | $ | 6,395 |  |  | $ | 8,132 |
Estimated earnings |  |  | 3,023 |  |  |  | 3,869 |
|  |  | 9,418 |  |  |  | 12,001 |
Less: Billings to date on uncompleted contracts |  |  | 9,202 |  |  |  | 11,776 |
|  | $ | 216 |  |  | $ | 225 |
Costs and estimated earnings in excess of billings on uncompleted contracts |  | $ | 495 |  |  | $ | 665 |
Billings in excess of costs and estimated earnings on uncompleted contracts |  |  | (279 | ) |  |  | (440 | )
|  | $ | 216 |  |  | $ | 225 |

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