Long-Term Debt (Details)	9 Months Ended
	Sep. 30, 2016 USD ($) Right	Dec. 31, 2015 USD ($)
Line of Credit Facility [Line Items]
Long-term debt	$ 0	$ 0
Tangible capital base amount	$ 27,000,000
Quick ratio	1.52
Performance Bond [Abstract]
Number of standby letters of credit | Right	9
Letter of credit and surety bonds	$ 3,300,000
Number of Performance and Bid Bonds issued in relation to contracts | Right	8
Number of stand by letters of credit deposited in escrow accounts | Right	9
Restricted cash and investments	$ 3,300,000	3,500,000
Restricted cash, current	1,601,000	1,771,000
Restricted cash, noncurrent	1,735,000	$ 1,779,000
Minimum [Member]
Line of Credit Facility [Line Items]
Tangible capital base of covenant amount	$ 10,500,000
Quick ratio, covenant	1.00
BB&T Bank [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Principal amount of the line of credit	$ 7,500,000
Expiration date of credit agreement	Mar. 31, 2017
Minimum cash balance requirement	$ 3,000,000
BB&T Bank [Member] | Revolving Credit Facility [Member] | Wall Street Journal Prime Rate [Member]
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate	4.50%