Contract Assets and Contract Liabilities (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Costs and estimated earnings on uncompleted contracts
Costs incurred on uncompleted contracts	$ 11,307,975	$ 3,681,965
Estimated earnings to date on uncompleted contracts	838,615	328,273
Gross contract assets	12,146,590	4,010,238
Less: billings to date	(13,221,152)	(5,622,111)
Net contract assets (liabilities)	$ (1,074,562)	$ (1,611,873)

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 910
-SubTopic 310
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=68065756&loc=d3e49370-109356

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.3(c)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant