Costs and Estimated Earnings on Uncompleted Contracts (Narrative) (Details) - Customer Concentration Risk [Member] - Contract with Customer [Member] - customer	3 Months Ended	12 Months Ended
Mar. 31, 2020	Dec. 31, 2019
Concentration Risk [Line Items]
Number of significant customers	8	8
Concentration risk percentage	93.30%	94.40%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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