Costs and Estimated Earnings on Uncompleted Contracts (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Costs and estimated earnings on uncompleted contracts
Costs incurred on uncompleted contracts	$ 3,681,965	$ 316,722
Provision for loss on uncompleted contracts
Estimated earnings to date on uncompleted contracts	328,273	40,488
Cost on uncompleted contracts, net	4,010,238	357,210
Less: billings to date	(5,622,111)	(372,339)
Costs and estimated earnings on uncompleted contracts, net	$ (1,611,873)	$ (15,129)

Costs incurred on uncompleted contracts.

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Estimated income loss on uncompleted contracts.

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Amount billed to customers under long-term contracts or programs but not paid. Excludes amounts due that have been withheld because of retainage provisions in a contract.

+ References

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Amount billed to customers under long-term contracts or programs that have been withheld because of retainage provisions in a contract.

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Amount of receivable reflecting the cost incurred on uncompleted contracts in excess of related billings.

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Cumulative provision for contract losses not offset against related costs accumulated on the balance sheet.

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